| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.60 |
| Score | 0% | 72% |
Which of these materials is not a good conductor of electricity?
air |
|
tin |
|
copper |
|
gold |
All conductors have resistance and the amount of resistance varies with the element. In general, metals make the best conductors of electricity and non-metals make the worst conductors of electricity.
Why is an insulator a poor conductor of electricity?
an insulator has many free electrons |
|
an insulator is made of inorganic material |
|
an insulator has few free electrons |
|
an insulator is made of organic material |
Insulators have valence shells that are more than half full of electrons and, as such, are tightly bound to the nucleus and difficult to move from one atom to another.
The diameter of a number 12 wire is __________ the diameter of a number 6 wire?
double |
|
triple |
|
less than |
|
more than |
The larger the number the smaller the diameter of the wire. So, the diameter of a number 12 wire is less than the diameter of a number 6 wire.
Which of the following can conduct electricity under some conditions but not others?
insulator |
|
semiconductor |
|
conductor |
|
resistor |
Semiconductors have valence shells that are exacly half full and can conduct electricity under some conditions but not others. This property makes them useful for the control of electrical current.
Which of the following is a difference between a circuit breaker and a fuse?
all of these |
|
a circuit breaker can be reused |
|
a fuse is cheaper than a circuit breaker |
|
a fuse responds more quickly than a circuit breaker |
Like fuses, circuit breakers stop current flow once it reaches a certain amount. They have the advantage of being reusable (fuses must be replaced when "blown") but respond more slowly to current surges and are more expensive than fuses.