Science Unit 7

Which of these materials is a conductor?

• rubber

• gold

• chalk

• glass

What is one use for an insulator?

• It slows down the flow of electric current to produce heat and light

• it stores electric energy for later use

• it allows electric current to flow through it

• It makes electrically charged objects safe to handle

Electric current cannot flow in a series if:

• the circuit contains and insulator

• there is a break in the circuit

• the circuit contains a resistor

• the circuit has only one loop in it

One example of a resistor is:

• a power cord

• a parallel circuit

• a battery

• a filament

What will happen in a parallel circuit if one of its loops is broken?

• electric current will not flow through any of the loops

• electric current will still flow through the broken loop

• electric current will still flow through the unbroken loops

• the energy source will stop providing energy to move electric charges

Which of the following is caused by the energy of motion?

• resistor

• friction

• conductor

• filament

Which of the following uses resistors to transform electricity into heat?

• a toaster

• a car engine

• a gas stove

• a wind turbine

Which of the following groups of materials make the best insulators?

• gold, wood, copper

• copper, plastic, gold

• rubber, plastic, glass

• graphite, glass, wood

An engineer is designing a new type of electrical wire. He wants to make sure that electricity will flow through the wire very easily. He tests four materials and performs each test several times to make sure that the results are accurate. Based on the results in the table, which material would be best for the new type of electrical wire?

• Material A

• Material B

• Material C

• Material D

La Tonya claims electricity travels only in a closed path. Which observation best supports her claim?

• The speaker came on when all the wires were connected, but it did not when on wire was disconnected.

• The speaker turned faster when I used two batteries than it did when I used only one battery.

• The speaker switched direction when I switched wires.

• The speaker slowed down when the battery started to wear out.