Final Exam Review Practice #1

If the above charges are attracted, the second charge must be

• neutral

• positive

• negative

Answer explanation

If the charges are attracted, it means they have opposite signs. Since the first charge is positive, the second charge must be negative to be attracted to it.

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

Electrical current will pass most easily through:

• an insulator

• a conductor

• a semiconductor

Answer explanation

Electrical current passes most easily through a conductor due to its ability to allow the flow of electrons.

Which of the following could be a good conductor of electricity?

• A metal pot

• A ceramic coffee cup

• A piece of foam packing material

Answer explanation

A metal pot is a good conductor of electricity due to its metallic properties that allow the flow of electrons.

In a good insulator, electrons are usually

• not moving at all

• free to move around after an impurity has been added

• free to move around

• tightly bound in place

Answer explanation

In a good insulator, electrons are tightly bound in place, restricting their movement and making the material a poor conductor of electricity.

If two negative charges are held close together and then released, the charges will

• accelerate toward each other

• accelerate away from each other

• not move

• move at a constant speed away from each other

Answer explanation

If two negative charges are held close together, they will accelerate away from each other due to the repulsive force between like charges.

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

The primary reason a bird can perch harmlessly on bare high voltage wires is that

• a bird's feet are close together

• a bird has a very large electrical resistance

• there is no potential difference across the bird's feet

• all of the above

Answer explanation

The correct choice is that there is no potential difference across the bird's feet, allowing it to perch harmlessly on bare high voltage wires.

A closed circuit is a circuit in which charge

• can flow

• is prevented from flowing

Answer explanation

In a closed circuit, charge can flow because the circuit forms a complete loop allowing the movement of charge.

Almost all of the electrons flowing through a battery circuit come from:

• the wires in the circuit

• chemical reactions of the light bulbs

• the battery

Answer explanation

Almost all of the electrons flowing through a battery circuit come from the battery itself, as it is the power source providing the electrical energy for the circuit.

Current from a battery is always

• DC.

• AC.

Answer explanation

Current from a battery is always DC, which stands for Direct Current. This means that the flow of electric charge is in one direction only.

Electrical resistance is measured in

• volts.

• amperes.

• joules.

• ohms.

Answer explanation

Electrical resistance is measured in ohms, not volts, amperes, or joules. Ohms is the correct unit for resistance.