High School Physics : Electricity and Magnetism

年代tudy concepts, example questions & explanations for High School Physics

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Example Questions

Example Question #2 :Understanding The Right Hand Rules

A current runs through a straight wire from right to left. What direction would the magnetic field be?

Possible Answers:

Right to left

Out of the screen

从左到右

Counter-clockwise

Into the screen

Correct answer:

Counter-clockwise

Explanation:

对于这个问题,用右手定则。花哟ur right hand, stick your thumb straight up and curl your fingers around in a "thumbs up" shape.

If your thumb is the current, your fingers will be the magnetic field. With your thumb pointing to the left (the direction of the current), your fingers will curl in a counter-clockwise direction.

Note that the right hand rule for a straight wire is different from the right hand rule for a planar magnetic field!

Example Question #3 :Understanding The Right Hand Rules

A straight wire carries a current directly into your computer screen. In what direction would the magnetic field be?

Possible Answers:

Right to left

Clockwise

Into the screen

Out of the screen

Counter-clockwise

Correct answer:

Clockwise

Explanation:

对于这个问题,用右手定则。花哟ur right hand, stick your thumb straight up, and curl your fingers around in a "thumbs up" shape.

If your thumb is the current, your fingers will be the magnetic field. With your thumb pointing away from your face, or toward your computer screen (the direction of the current), your fingers will curl in a clockwise direction.

Note that the right hand rule for a straight wire is different from the right hand rule for a planar magnetic field!

Example Question #4 :Understanding The Right Hand Rules

A straight wire carries a current directly out of your computer screen. In what direction would the magnetic field be?

Possible Answers:

从左到右

Counter-clockwise

Into the screen

Clockwise

Out of the screen

Correct answer:

Counter-clockwise

Explanation:

对于这个问题,用右手定则。花哟ur right hand, stick your thumb straight up, and curl your fingers around in a "thumbs up" shape.

If your thumb is the current, your fingers will be the magnetic field. With your thumb pointing toward your face, or out from your computer screen (the direction of the current), your fingers will curl in a counter-clockwise direction.

Note that the right hand rule for a straight wire is different from the right hand rule for a planar magnetic field!

Example Question #5 :Understanding The Right Hand Rules

A negatively charged particle is moving to the right along a vertical plane. If the force generated by a constant magnetic field is directed upwards within plane, in what direction is the magnetic field?

Possible Answers:

Downwards within the plane

Out of the plane, away from the observer

Upward within the plane

Out of the plane, toward the observer

Correct answer:

Out of the plane, toward the observer

Explanation:

This question requires you to apply the right hand rule. Your thumb will point to the right, in the direction of the particle's velocity. For the negatively charged particle to feel an upward force, the back of your hand,not your palm as would be the case with a positively charged particleneeds to be facing up. Extension of your fingers makes the magnetic field point out of the plane, toward you.

Example Question #1 :Magnetism And Electromagnetism

A current ofruns through a straight wire. If the resulting magnetic field is, what is the radius of the field?

Possible Answers:

Correct answer:

Explanation:

Ampere's law states:

.

In other words, the magnetic field (), is equal to a constant () times the current () divided by the circumference of the magnetic field it is creating.

We are given the current, the constant, and the magnetic field strength. Using these values, we can solve for the magnetic field radius.

Notice that thecancels out.

Example Question #1 :Electric Charge

Materials in which the electrons are bound very loosely to the nuclei and can move about freely within the material are referred to as

Possible Answers:

年代emiconductors

年代uperconductors

Conductors

Insulators

Correct answer:

Conductors

Explanation:

Conductors allow the electrons to flow freely along it. That is why metal; is considered a good conductor. It allows the electrons to flow through it which is why it is used in wire in an an electric circuit.

Example Question #2 :Electric Charge

A glass rod is rubbed with a piece of silk. During the process the glass rod acquires a positive charge. The silk

Possible Answers:

保持中立

Could either be positively charged or negatively charged. It depends on how hard the rod was rubbed.

Acquires a positive charge as well

Acquires a negative charge

Correct answer:

Acquires a negative charge

Explanation:

年代ince the glass rod acquires a positive charge, this means that it is deficient in electrons. Since the rod was rubbed by the piece of silk, the silk is what now collects the electrons. The silk now has an excess of electrons which means that the silk is now negatively charged.

Example Question #3 :Electric Charge

A charged rod carrying a negative charge is brought near two spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres?

Possible Answers:

The spheres do not get any charge

The sphere near the charged rod becomes positive and the other becomes negative

None of these

The sphere near the charged rod becomes negative and the other becomes positive

Correct answer:

The sphere near the charged rod becomes positive and the other becomes negative

Explanation:

When the negatively charged rod is brought near one of the two spheres, the presents of the negative charge will induce a flow of charge in the spheres such that regions farthest away from the charged rod will become most negative and regions near the rod will become most positive. This is called charge by induction.

Example Question #4 :Electric Charge

By what method will a positively charged rod produce a negative charge on a conducting sphere that is placed on an insulating surface?

Possible Answers:

Charge by conduction

Charge by induction

None of these

Charge by convection

Correct answer:

Charge by induction

Explanation:

Charge by induction happens when a charged object is brought in the vicinity of a neutral object. The presents of the charged object will cause the free charges in the neutral object to shift such that the neutral object becomes polarized. When the charged object is positive, this will induce a negative charge on a neutral object.

Example Question #5 :Electric Charge

How many electrons make up a charge of?

Possible Answers:

Correct answer:

Explanation:

The charge of a single electron is

We can then convert the amount of charge to determine the number of electrons.

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