| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.73 |
| Score | 0% | 75% |
This circuit component symbol represents a(n):
diode |
|
transistor |
|
inductor |
|
capacitor |
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 the following is a difference between a circuit breaker and a fuse?
a fuse is cheaper than a circuit breaker |
|
a circuit breaker can be reused |
|
a fuse responds more quickly than a circuit breaker |
|
all of these |
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.
The valence shell of a semiconductor is how full of electrons?
half full |
|
empty |
|
more than half full |
|
less than half full |
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 statements about a capacitor is false?
it is safe to touch a capacitor with your hands as long as it is small |
|
to discharge a capacitor safely, use a high-wattage resistor comparable to the capacitance of the capacitor |
|
a capacitor remains charged even after the input voltage is removed |
|
you should always discharge any capacitors before working on an electronic circuit |
The purpose of a capacitor is to retain electric charge and it will do so even after its input voltage is removed. After the input voltage is removed, the capacitor will slowly discharge but, depending on the size and characteristics of the capacitor, discharging could take from a few minutes to a few years. So, it's never safe to touch a capacitor with your hands and you should make sure to discharge any capacitors in a circuit before working on it using an appropriately high-wattage resistor or a capacitor discharge tool.
The watt is a unit of measurement for:
resistance |
|
frequency |
|
power |
|
energy |
Electrical power is measured in watts (W) and is calculated by multiplying the voltage (V) applied to a circuit by the resulting current (I) that flows in the circuit: P = IV. In addition to measuring production capacity, power also measures the rate of energy consumption and many loads are rated for their consumption capacity. For example, a 60W lightbulb utilizes 60W of energy to produce the equivalent of 60W of heat and light energy.