8th Grade Science - Electricity

____________ is an object's physical property that results in an electric force being applied to other objects that have the same physical property.
Check which statements below are true:
1. Objects that have the same charge attract.
2. Objects that have opposite charges attract.
3. The force between charged objects is an electric force.
4. An electric field is the space around charged and uncharged objects.
5. Atoms that have the same number of electrons as protons usually do not have a charge.
When an object consisting of atoms loses electrons, it:
1. becomes positively charged
2. becomes negatively charged
3. stays neutral
A material in which charges cannot move freely is an electrical ____________.
___________ is an example of a rapid electric discharge that occurs between clouds and the ground or another part of the cloud.
An electric ___________ is the rate at which charges pass through given point.
In an electric current, charges and electrons move at the same rate past a given point.
1. True
2. False
The potential difference between two points in a circuit is called ____________.
Factors that can determine the resistance of an object include:
(Check all that apply.)
1. smell
2. material
3. length
4. color
5. temperature
Cells convert which type of energy to electrical energy?
1. light
2. nuclear
3. chemical
4. magnetic
Which equation below describes Ohm's law?
1. I = V x R
2. V = I x R
3. R = V x I
4. R = I/V
The rate at which electrical energy is converted into other forms of energy is:
1. electric current
2. electric voltage
3. electric power
4. electric flow
5. energy is never given off.
The equation for power is:
1. V = P x I
2. P = V x I
3. I = P x V
4. P = V / I
The equation for Electrical Energy is:
1. E = P x t
2. E = P / t
3. E = V x I
4. E = V/ R
An electrical energy source, a load and a wire that connects them make up an electric ___________ .
An electric circuit in which the parts are joined in branches such that the potential difference across each branch is the same, is a __________ circuit.
1. series
2. parallel
3. open
Devices that automatically open when the current in an electric circuit is too high include:
1. batteries
2. fuses
3. light switches
4. circuit breakers
5. resistors
When a switch in an electric circuit is opened, the electric current can flow in the circuit.
1. True
2. False
How much energy does a 75 W light bulb use if it is used for 500 hours?

___________ kWh
Material that attracts iron or material made from iron is called a __________.
A magnet's north pole points to the Earth's
1. South pole
2. North pole
3. Center
4. atmosphere
In order for a magnetic field to exist in an object, the electric charge must be:
1. stationary
2. changing from positive to negative
3. moving or spinning
In materials such as iron, atoms line up in tiny areas called __________ and create a strong magnetic field.
Electromagnetism is the interaction between:

(Check all that apply.)
1. electricity
2. gravity
3. magnetism
4. solar radiation
To build an electromagnet you need:

(Check all that apply.)
1. a magnetized core
2. air
3. a solenoid
4. an electrical energy source
An electric motor converts electrical energy primarily into:
1. solar energy
2. mechanical energy
3. chemical energy
4. thermal energy
In order for a current in a circuit to be produced by the process of electromagnetic induction, the magnetic field must ne:
1. constant
2. changing
An electrical generator uses electromagnetic induction to change:
1. mechanical energy to electrical energy
2. electrical energy to mechanical energy
3. solar energy to electrical energy
4. thermal energy to mechanical energy
A device that uses induction to increase or decrease the voltage of alternating current is a ______________.
An electric current produced by a generator that changes direction each time the generator coil makes half a turn is:
1. a direct current
2. an alternating current