| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.60 |
| Score | 0% | 72% |
Silver and gold are among the most highly conductive elements. Why is copper used much more often as a conductor in electrical circuits?
copper is durable and relatively cheap |
|
silver and gold are costly |
|
silver and gold are brittle |
|
all of these |
All conductors have resistance and the amount of resistance varies with the element. But, resistance isn't the only consideration when choosing a conductor as the most highly conductive elements like silver and gold are also more expensive and more brittle than slightly less conductive elements like copper. A balance needs to be struck between the electrical qualities of a material and its cost and durability.
This circuit component symbol represents a(n):
capacitor |
|
transformer |
|
inductor |
|
resistor |
An inductor is coiled wire that stores electric energy in the form of magnetic energy and resists changes in the electric current flowing through it. If current is increasing, the inductor produces a voltage that slows the increase and, if current is decreasing, the magnetic energy in the coil opposes the decrease to keep the current flowing longer. In contrast to capacitors, inductors allow DC to pass easily but resist the flow of AC.
A capacitor is often used for which of the following purposes?
to maintain power in a circuit when the primary power source is disconnected |
|
to allow a small amount of current to control a large amount of current |
|
as a primary power source |
|
to convert alternating current into direct current |
Capacitors store electricity and are used in circuits as temporary batteries. Capacitors are charged by DC current (AC current passes through a capacitor) and that stored charge can later be dissipated into the circuit as needed. Capacitors are often used to maintain power within a system when it is disconnected from its primary power source or to smooth out or filter voltage within a circuit.
This circuit component symbol represents a(n):
inductor |
|
capacitor |
|
diode |
|
transistor |
A diode allows current to pass easily in one direction and blocks current in the other direction. Diodes are commonly used for rectification which is the conversion of alternating current (AC) into direct current (DC). Because a diode only allows current flow in one direction, it will pass either the upper or lower half of AC waves (half-wave rectification) creating pulsating DC. Multiple diodes can be connected together to utilize both halves of the AC signal in full-wave rectification.
Which of these materials is not a good conductor of electricity?
tin |
|
gold |
|
copper |
|
air |
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.