The Sciences An Integrated Approach, 8th Edition by James Trefil, Robert M. Hazen tb2 – Test Bank

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Package Title: Test Bank

Course Title: Trefil8e

Chapter Number: 5

 

 

Question Type: Multiple Choice

 

 

1) Motors and magnets owe their existence to what force?

 

  1. a) strong force
  2. b) weak force
  3. c) gravitational force
  4. d) static electrical force
  5. e) electromagnetic force

 

Answer: e

 

Difficulty: Easy

Learning Objective: LO 5.1 Explain why change in the state of an object’s motion implies the action of a force on the object.

Section Reference: Section 5.1 Nature’s Other Forces

 

 

2) Our basic knowledge of the properties of static electricity began:

 

  1. a) in the sixteen hundreds.
  2. b) with the invention of the battery.
  3. c) with the invention of the electric motor.
  4. d) in the eighteenth century.
  5. e) in the seventeenth century.

 

Answer: d

 

Difficulty: Easy

Learning Objective: LO 5.1 Explain why change in the state of an object’s motion implies the action of a force on the object.

Section Reference: Section 5.1 Nature’s Other Forces

 

 

3) In his famous experiment of the late 1700s, Charles Coulomb:

 

  1. a) repeated Benjamin Franklin’s kite and lightning demonstration.
  2. b) measured static electricity using a piece of amber.
  3. c) proved Newton’s three laws of motion.
  4. d) measured the force of the electric charge in objects.
  5. e) showed that muscle contractions are both electric and chemical.

 

Answer: d

 

Difficulty: Easy

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

 

 

4) Coulomb discovered that the electrical force equation was very similar to the force equation ________ had discovered.

 

  1. a) Benjamin Franklin
  2. b) James Clerk Maxwell
  3. c) Isaac Newton
  4. d) Thomas Edison
  5. e) Michael Faraday

 

Answer: c

 

Difficulty: Medium

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

 

 

5) In what way does Newton’s law of universal gravitation differ from Coulomb’s law?

 

  1. a) Electrical forces can be either attractive or repulsive, while gravity is only attractive.
  2. b) Only Newton’s law of gravity requires a universal constant.
  3. c) Only Coulomb’s law addresses distance in describing the effect of one object on another.
  4. d) Newton’s law required experimentation but Coulomb’s law did not.
  5. e) Newton’s and Coulomb’s laws are really identical, so there is no significant difference.

 

Answer: a

 

Difficulty: Medium

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

 

 

6) How is the force of two charged particles related to their charges?

 

  1. a) proportional to the product of their charges divided by the cube of the distance between them
  2. b) proportional to the product of their charges divided by the square of the distance between them
  3. c) proportional to the ratio of their charges divided by the distance between them
  4. d) proportional to the ratio of their charges multiplied by the square of the distance between them
  5. e) No known relation exists between charged particles and force.

 

Answer: b

 

Difficulty: Medium

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

 

 

7) Coulomb’s law states that force is dependent on all the following except:

 

  1. a) the Coulomb constant.
  2. b) the sizes of the two objects.
  3. c) the charge of the smaller object.
  4. d) the distance between the two objects.
  5. e) the charge of the larger object.

 

Answer: b

 

Difficulty: Medium

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

 

 

8) The lines of force radiating from a charged object is called a/an:

 

  1. a) gravitational field.
  2. b) gravitational force.
  3. c) electrical field.
  4. d) electrical force.
  5. e) magnetic field.

 

Answer: c

Difficulty: Easy

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

 

 

9) What are some ways the Earth’s magnetic field is or was used for navigation?

 

  1. a) Sailors of the past used compasses to direct their course.
  2. b) Some bacteria navigate up and down within pond ooze.
  3. c) Some migratory birds are directed by the magnetic field.
  4. d) The Australian silvereye can see the magnetic fields using a form of color vision.
  5. e) All of the choices are ways in which the magnetic field is or was used for navigation.

 

Answer: e

 

Difficulty: Easy

Learning Objective: LO 5.3 Describe the properties of a magnetic field.

Section Reference: Section 5.3 Magnetism

 

 

10) William Gilbert discovered many important properties of magnets. Which of the following was not among Gilbert’s findings?

 

  1. a) Every magnet has at least two poles.
  2. b) If magnetic poles are alike they repel each other.
  3. c) Steel rods can be magnetized by stroking them with a lodestone.
  4. d) Electric currents can be produced by changing magnetic fields.
  5. e) Iron’s magnetism can be destroyed by heating.

 

Answer: d

 

Difficulty: Easy

Learning Objective: LO 5.3 Describe the properties of a magnetic field.

Section Reference: Section 5.3 Magnetism

 

 

11) When you cut a magnet in half you get:

 

  1. a) two north poles.
  2. b) two south poles.
  3. c) two magnets each with a north pole and south pole.
  4. d) one magnetic monopole.
  5. e) one south pole and one north pole.

 

Answer: c

 

Difficulty: Medium

Learning Objective: LO 5.3 Describe the properties of a magnetic field.

Section Reference: Section 5.3 Magnetism

 

 

12) Mary Shelley’s Frankenstein was inspired by some experiments and demonstrations in electricity based upon:

 

  1. a) Galvani’s research.
  2. b) Voltaire’s research.
  3. c) the writings of Alessandro Volta.
  4. d) Benjamin Franklin’s research.
  5. e) William Gilbert’s compass.

 

Answer: a

 

Difficulty: Easy

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

13) What scientist is credited with making the first battery?

 

  1. a) Luigi Galvani
  2. b) Michael Faraday
  3. c) Alessandro Volta
  4. d) Benjamin Franklin
  5. e) William Gilbert

 

Answer: c

 

Difficulty: Easy

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

14) Every electrical circuit contains:

 

  1. a) an electromagnet.
  2. b) an unbroken flow path.
  3. c) an electric switch.
  4. d) a circuit breaker.
  5. e) a motor.

 

Answer: b

 

Difficulty: Easy

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

15) One amp of electrical current is equal to:

 

  1. a) one newton per second.
  2. b) one coulomb of charge per second.
  3. c) one thousand watts per hour.
  4. d) one volt times one amp.
  5. e) one amp divided by one volt per second.

 

Answer: b

 

Difficulty: Easy

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

16) Which of the following items would use only low-resistance wires?

 

  1. a) a toaster
  2. b) a space heater (electric heater for a room in your house)
  3. c) an electrical transmission line
  4. d) an incandescent light bulb
  5. e) a hair dryer

 

Answer: c

 

Difficulty: Hard

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

17) Ohm’s Law states:

 

  1. a) electrical pressure = flow charge/flow resistance.
  2. b) current = voltage (volts) + flow charge (coulombs).
  3. c) power (watts) = current (amps) x voltage (volts).
  4. d) voltage (volts) = current (amps) x resistance (ohms).
  5. e) voltage (volts) = pressure (ohms) x resistance (ohms).

 

Answer: d

 

Difficulty: Easy

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

18) In the equation for Ohm’s law, resistance is in the unit:

 

  1. a) volts.
  2. b) amps.
  3. c) ohms.
  4. d) watts.
  5. e) coulombs.

 

Answer: c

 

Difficulty: Easy

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

19) The load in an electric hair dryer is located:

 

  1. a) where the dryer plugs into the electrical outlet.
  2. b) where the electrical cord is attached to the dryer.
  3. c) in the on/off switch.
  4. d) in the heating element and fan.
  5. e) where the heated air is exhausted.

 

Answer: d

 

Difficulty: Medium

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

20) How much amperage will be moving through a wire if it has a resistance of 12 ohms and is carrying 120 V?

 

  1. a) 10 amps
  2. b) 12 amps
  3. c) 1.2 amps
  4. d) 100 amps
  5. e) 1 amp

 

Answer: a

 

Difficulty: Medium

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

21) Approximately how much electrical current will flow through a 250-watt stereo system to play a compact disk in the United States?

 

  1. a) 0.5 amps
  2. b) 1 amp
  3. c) 2 amps
  4. d) 25 amps
  5. e) 250 amps

 

Answer: c

 

Difficulty: Hard

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

22) Approximately how much power is consumed per hour by an electric stove drawing 40 amps? (Note – This electric stove is plugged into a 240 volt wall socket.)

 

  1. a) 6 watts/hour
  2. b) 345 watts/hour
  3. c) 9.6 kilowatts/hour
  4. d) 5.75 kilowatts/hour
  5. e) 9600 kilowatts/hour

 

Answer: c

 

Difficulty: Medium

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

23) Hans Christian Oersted discovered the relationship between the forces of magnetism and electricity by:

 

  1. a) many long years of tedious research.
  2. b) reading the writings of Galvani.
  3. c) an accident during a physics lecture.
  4. d) interpreting his dreams and obsessions.
  5. e) replicating the experiments of Volta.

 

Answer: c

 

Difficulty: Easy

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

 

 

24) Which of the following can produce magnetic fields?

 

  1. a) gravitational force
  2. b) static electrical force
  3. c) moving electrical charges
  4. d) flowing water or other liquids
  5. e) rubbing amber

 

Answer: c

 

Difficulty: Medium

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

 

 

25) The functioning of an electric motor depends on the fact that:

 

  1. a) like charges attract, unlike charges repel.
  2. b) like magnetic poles attract, unlike magnetic poles repel.
  3. c) an electrical current produces a magnetic field.
  4. d) permanent magnets are always stronger than electromagnets.
  5. e) all motors must have several electromagnets.

 

Answer: c

 

Difficulty: Medium

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

 

 

26) Electric fields and electric currents can be produced by:

 

  1. a) changing magnetic fields.
  2. b) radiation.
  3. c) magnetic monopoles.
  4. d) certain magnetic bacteria.
  5. e) static electrical charges.

 

Answer: a

 

Difficulty: Easy

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

 

 

27) What important practical device followed directly from Michael Faraday’s work?

 

  1. a) the battery
  2. b) the thermostat
  3. c) the electromagnet
  4. d) the electric switch
  5. e) the electric generator

 

Answer: e

 

Difficulty: Easy

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

 

 

28) Whose experimental work lead to the first electric generator?

 

  1. a) Benjamin Franklin
  2. b) James Clerk Maxwell
  3. c) Isaac Newton
  4. d) Thomas Edison
  5. e) Michael Faraday

 

Answer: e

 

Difficulty: Medium

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

 

 

29) Which device would most likely be running on DC electricity?

 

  1. a) a desktop computer.
  2. b) a toaster.
  3. c) the microwave oven in your house.
  4. d) your cell phone in your pocket.
  5. e) your home stereo.

 

Answer: d

 

Difficulty: Hard

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

 

 

30) Which is not true based on Maxwell’s equations?

 

  1. a) Like charges attract, unlike charges repel.
  2. b) Coulomb’s law applies to the equations.
  3. c) There are no magnetic monopoles in nature.
  4. d) Magnetic phenomena can be produced by electrical effects.
  5. e) Electrical phenomena can be produced by magnetic effects.

 

Answer: a

 

Difficulty: Medium

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

 

 

Question Type: True/False

 

 

31) Electricity and magnetism is one aspect of two forces.

 

Answer: False

 

Difficulty: Easy

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

 

 

32) Static electricity exists when there is an unbalance between the number of electrons and neutrons within an object.

 

 

Answer: False

 

Difficulty: Easy

Learning Objective: LO 5.1 Explain why change in the state of an object’s motion implies the action of a force on the object.

Section Reference: Section 5.1 Nature’s Other Forces

 

 

33) Benjamin Franklin named the charges positive and negative.

 

Answer: True

 

Difficulty: Easy

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

 

 

34) Electrons far from the nucleus tend to be held loosely to it. .

 

Answer: True

 

Difficulty: Easy

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

 

 

35) Gravity is a much stronger force than electromagnetism.

 

Answer: False

 

Difficulty: Easy

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

 

 

36) The north pole of the earth is the south pole of the magnetic field of the earth.

 

Answer: True

 

Difficulty: Easy

Learning Objective: LO 5.3 Describe the properties of a magnetic field.

Section Reference: Section 5.3 Magnetism

 

 

37) Some migratory birds use magnets within their body to guide them.

 

Answer: True

 

Difficulty: Easy

Learning Objective: LO 5.3 Describe the properties of a magnetic field.

Section Reference: Section 5.3 Magnetism

 

 

38) In a series circuit the loads are linked by a single wire.

 

Answer: True

 

Difficulty: Easy

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

 

 

39) If you had one atom of iron it would only have a north or south magnetic field and whether it were a north or south pole would depend on the direction of spin of the electron.

 

Answer: False

 

Difficulty: Easy

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

 

 

40) The cell phone in your pocket works on DC current.

 

Answer: True

 

Difficulty: Easy

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

 

 

Question Type: Essay

 

 

41) What is the difference between series and parallel circuits?

 

Answer:

 

Difficulty: Easy

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

Solution: While both circuits carry an electric signal along an unbroken path, a series circuit has two or more loads linked along a single wire loop; the parallel circuit has different loads on different wire loops. The load is where the useful work is done; for example, the light bulb filament.

 

 

42) Describe how the electromagnet operates.

 

Answer:

 

Difficulty: Easy

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

Solution: A magnetic field is created around a loop of wire in which an electric current is moving. This field has a “north” and a “south” pole orientation as long as the current is moving.

 

 

43) What are the three components of every electric circuit?

 

Answer:

 

Difficulty: Easy

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

Solution: The components are a source of energy like a battery, a closed path through which current can flow, and a device such as a motor or light bulb that uses the electrical energy.

 

 

44) Can a magnetic monopole ever be created from ordinary magnets? Why or why not?

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

Solution: No. The magnetism of a material is created from the cumulative effects of the paths taken by electrons around the nucleus of the individual atoms. Even if the material could be divided into parts the size of an atom, there would still be a dipole field from the electrons of that one atom. Dividing the material to the subatomic level destroys the magnetism and other traits intrinsic to the material.

 

 

45) How could you make an electromagnet?

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

Solution: You would have to wrap wire around a central metal bar.

 

 

46) Who developed the first battery and upon whose work was this development based?

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

Solution: Alessandro Volta developed the first battery. His work was based on investigations into the studies of Luigi Galvani, who was using electric sparks to cause amputated frog legs and other animal parts to move.

 

 

47) Compare alternating current with direct current. Give examples of each type of current.

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

Solution: Alternating current (AC) is a type of electric current in which charges in the electric coils respond to the alternating direction of current from a rotating wire coil in a magnetic field. Examples include all household appliances in the United States. Direct current (DC) is a current in which the electrons flow in one direction only. An example would be the chemical reaction in a battery.

 

 

48) Describe events at the atomic level when a thunderstorm results in the lightning strike of a tall tree.

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

Solution: During the storm, wind and rain interrupt the neutral distribution of electrons in the clouds. When the charged cloud passes over the tall tree a violent electric discharge occurs. This discharge (lightning) results from positive charges moving from the ground to meet the negative charges moving from the bottom of the clouds.

 

 

49) How does a magnetic compass work?

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.3 Describe the properties of a magnetic field.

Section Reference: Section 5.3 Magnetism

Solution: A compass needle is a magnet that will align itself in the direction of the magnetic north and south poles of the earth. The compass will do this because the Earth itself is a giant magnet with a north pole in Canada and a south pole in Antarctica.

 

 

50) How does a nerve in a living organism carry an electrical signal?

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

Solution: Positively and negatively charged ions move in response to an electrical stimulus, distorting the axon membrane and transmitting the signal to the end of the nerve. Neurotransmitters relay the signal across a gap to the next nerve in position.

 

 

51) Explain the operation of a car battery.

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

Solution: A battery is made of alternating plates of two kinds of material such as lead and lead oxide, immersed in a bath of sulfuric acid. When the battery is being discharged, the lead plate interacts with the acid, producing lead sulfate and some free electrons. The electrons move through an external wire to other plates where the process is repeated. The free electrons move from the battery to the ignition of the car.

 

 

52) How does electricity differ from gravity?

 

Answer:

 

Difficulty: Hard

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

Solution: Although both electricity and gravity are forces, a gravitational force always pulls two objects together while an electric force can attract some objects toward each other and repel others away from each other.

 

 

53) What is the main difference between an electric motor and an electric generator?

 

Answer:

 

Difficulty: Hard

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

Solution: An electric motor converts electrical energy into kinetic energy of a spinning shaft. An electric generator does the opposite: converts the kinetic energy of a spinning shaft into electrical energy.

 

 

54) Explain how an electric motor works.

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.5 Explain the relationship between electricity and magnetism.

Section Reference: Section 5.5 Connections Between Electricity and Magnetism

Solution: Though the design of electric motors differs, they all contain either two electromagnets or an electromagnet and a permanent magnet. In either case the idea is to pass a current through the coil making up the armature and create a torque. You need a way to alternate the flow of electrons and depending on the type of motor there are various ways to do this.

 

 

55) List Maxwell’s equations (in statement form). Explain at least one of these equations by

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

Solution: Maxwell’s equations include Coulomb’s law (like charges repel, unlike attract), the fact that there are no magnetic monopoles in nature, magnetic phenomena can be produced by electrical effects, and electrical phenomena can be produced by magnetic effects. For example, we can generate electricity by using the natural connection between electricity and magnetism.

 

 

56) Explain how someone shipwrecked on an island might “discover” and use electricity.

 

Answer:

 

Difficulty: Hard

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

Solution: The simplest electricity to make under these circumstances may be static electricity, which might be produced by rubbing natural materials together or harnessing lightning. If some magnetic components and wire were available, the shipwrecked person might experiment with them and find that electricity will naturally flow in wires that are related to magnetic fields. Some natural materials could be used to make a battery, and thus would make an electrical source.

 

 

57) Compare the flow path of electrical charges through a nerve cell with the electrical flow path of lightning.

 

Answer:

 

Difficulty: Hard

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

Solution: Electrons in motion follow a path in both examples. The source of the electrical charge is different, however. In clouds, there is interaction of water droplets, in living tissues the source of the charge is chemical energy.

 

 

58) At Earth’s magnetic poles, what becomes of the magnetic field of force lines?

 

Answer:

 

Difficulty: Hard

Learning Objective: LO 5.3 Describe the properties of a magnetic field.

Section Reference: Section 5.3 Magnetism

Solution: The field of force lines converge at or near the Earth’s magnetic poles.

 

 

59) If you were lost in unfamiliar territory, how could you make a compass for navigation?

 

Answer:

 

Difficulty: Hard

Learning Objective: LO 5.3 Describe the properties of a magnetic field.

Section Reference: Section 5.3 Magnetism

Solution: You would have to find a piece of lodestone and use a sliver of it (or beat or scrape a metal pin on the lodestone to magnetize it), and then suspend the lodestone sliver or metal pin by a thread or float it in water. Either way, the sliver or pin must hang freely so it can orient itself according to Earth’s magnetic field.

 

 

60) How did Galvani’s experiments challenge the eighteenth century doctrine of vitalism?

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

Solution: Galvani showed that electricity, which was not unique to the living organism but was a general force of nature, could cause movement or animation in once-living tissue like the muscles in frog’s legs.

 

 

61) What is fundamentally different in the way that a battery generates electricity versus an electric generator?

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

Solution: A battery relies on a chemical reaction to generate electrical current, whereas a generator uses electromagnetic effects.

 

 

62) How is increasing the amperage (number of amps) in a circuit like turning up the flow of water at a faucet?

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

Solution: The amp is a measure of the amount of current or the actual number of electrons flowing in a wire. This is measured in coulombs per second. The flow of water from a faucet is also measured in amount over time, so in this sense the “flow” is quite similar.

 

 

63) If the current (in amps) remains the same, but the voltage increases, what effect does this have on the power (in watts) consumed by some device?

 

Answer:

 

Difficulty: Medium

Learning Objective: LO 5.4 Discuss how the link between electricity and magnetism led to the discovery of the battery and electric circuit, including using Ohm’s law to solve problems.

Section Reference: Section 5.4 Batteries and Electric Circuits

Solution: Because power in watts is equal to current in amps multiplied by the voltage (in volts), an increase in voltage will increase the power used.

 

 

64) How did Michael Faraday get his start as a scientist?

 

Answer:

 

Difficulty: Easy

Learning Objective: LO 5.6 Describe the results of Faraday’s research in electromagnetism.

Section Reference: Section 5.6 Electrical Effects from Magnetism

Solution: He attended the lectures of Sir Humphry Davy, a world leader in physical and chemical research, and gained favor with Sir Humphry by transcribing notes from his lectures and having them bound in a book. This gift helped Faraday get a job as a laboratory assistant to Davy.

 

 

65) What was Benjamin Franklin’s contribution to the understanding of the electrical “fluid”?

 

Answer:

 

Difficulty: Easy

Learning Objective: LO 5.2 Explain the role of electrons in creating positive and negative electrical charge both qualitatively and quantitatively.

Section Reference: Section 5.2 Static Electricity

Solution: At the time that Mr. Franklin was conducting electrical experiments, it was thought that electricity came from the interaction of two different electrical “fluids,” but Franklin was able to show that it was a simpler explanation that electricity was the transfer of one fluid from one object to another. He realized that objects could have an excess or a deficiency of this fluid and he applied the names “negative” and “positive” to these two situations.

 

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