# High School Physics : Electric Charge

## Example Questions

### 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

Conductors

Insulators

Semiconductors

Superconductors

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 #1 : Electric Charge

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

Acquires a negative charge

Acquires a positive charge as well

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

Remains neutral

Acquires a negative charge

Explanation:

Since 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?

None of these

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

The spheres do not get any charge

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

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?

Charge by conduction

Charge by induction

None of these

Charge by convection

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 ?     Explanation:

The charge of a single electron is We can then convert the amount of charge to determine the number of electrons. ### Example Question #6 : Electric Charge

A neutral atom always has

The same number of neutrons and protons

The same number of protons and electrons

More protons than electrons

More neutrons than protons 