| 1. |
A capacitor consists of two conducting surfaces called plates, separated by an insulating material called the:
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| 2. |
Capacitance is the measure of the ability of a capacitor to:
| A. |
conduct a direct current |
| B. |
hold an electric charge |
| C. |
store current in a magnetic field |
| D. |
repel dynamic eddy currents |
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| 3. |
A farad is the capacity of a capacitor that stores a charge of one coulomb at a potential difference of:
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| 4. |
A coulomb is the charge that passes a point in one second when a:
| A. |
voltage of one volt is generated |
| B. |
couple of ohms are combined |
| C. |
current does not flow in any direction |
| D. |
current of one ampere flows |
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| 5. |
The charge on a capacitor can be determined using the formula:
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| 6. |
A 15 uF capacitor has been charged to a potential difference of 240 V. The charge on the capacitor will be:
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| 7. |
The capacitance of a capacitor varies according to three physical parameters. These are, the effective area of the plates, the distance between the plates and the:
| A. |
cross-sectional area of the plates |
| B. |
supply voltage characteristic |
| C. |
permittivity of the dielectric |
| D. |
type of connecting lead used |
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| 8. |
For a capacitor consisting of two parallel plates, the capacitance can be found from the following equation: 
In the formula symbol ‘A’ stands for:
| A. |
cross-sectional distance between the plates |
| B. |
distance between the plates in metres |
| C. |
absolute permittivity of the dielectric |
| D. |
area of the plates in square metres |
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| 9. |
The dielectric constant signifies the degree to which capacitance can be increased by replacing the:
| A. |
air between the plates with a dielectric |
| B. |
air between the plates with a vacuum |
| C. |
insulation between the plates with air |
| D. |
vacuum between the plates with air |
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| 10. |
For a capacitor, the voltage per unit thickness necessary to cause breakdown is called the:
| A. |
dielectric constant of the capacitor |
| B. |
dielectric strength of the insulating material |
| C. |
capacitance of the insulating material |
| D. |
electrostatic current limit of the capacitor |
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| 11. |
When capacitors are connected in series the total capacitance will be:
| A. |
more than the value of any one of the capacitors |
| B. |
the same value as the largest one of the capacitors |
| C. |
less than the value of any one of the capacitors |
| D. |
the same value as the smallest one of the capacitors |
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| 12. |
Look at the following diagram: 
A 10 uF and a 22 uF capacitor have been connected in series as shown in the above diagram. The total resulting capacitance will be approximately:
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| 13. |
Look at the following diagram: 
Two capacitors have been connected in series across a 24 V DC supply as shown. The voltage across the 33 uF capacitor will be:
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| 14. |
Placing two or more capacitors in parallel has the same effect as:
| A. |
increasing the distance between the plates |
| B. |
increasing the area of the plates |
| C. |
increasing the dielectric strength of the capacitors |
| D. |
decreasing the size of the connecting leads |
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| 15. |
Look at the following diagram: 
Two capacitors have been connected in parallel as shown. The total capacitance will be:
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| 16. |
When a capacitor is connected to DC supply a charging current will flow. This current:
| A. |
flows through the capacitor’s electrostatic field |
| B. |
will flow through the dielectric on each half cycle |
| C. |
flows through the insulating material in the circuit |
| D. |
does not flow through the capacitor |
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| 17. |
The time constant is the time taken for a capacitor to charge up to:
| A. |
63.2 % of the applied voltage |
| B. |
86.4 % of the applied voltage |
| C. |
95.0 % of the applied voltage |
| D. |
99.3 % of the applied voltage |
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| 18. |
Look at the following diagram: 
With reference to the time constant curve shown above, the percentage of the supply voltage on a capacitor three time constants after charging has commenced will be:
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| 19. |
Look at the following diagram: 
The time constant of the above circuit is:
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| 20. |
Look at the following diagram: 
With reference to the above circuit, if the capacitor has been charged to 24 V, then the time taken to discharge to 15.16 V will be:
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| 21. |
Look at the following diagram: 
With reference to the above circuit, if the capacitor is fully discharged and the switch connected to the charge position, the capacitor voltage will reach 20.74 V in:
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| 22. |
The energy stored in the capacitor can be found using the formula:
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| 23. |
A 47 uF capacitor has been charged from a 200 V DC supply. The energy stored in the capacitor will be:
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| 24. |
Care must be taken when working with large value capacitors as they can:
| A. |
supply alternating current in an intermittent pattern |
| B. |
change their value of capacitance when the supply is disconnected |
| C. |
store high voltages for a long time after the supply is disconnected |
| D. |
cause physical injury because of their extreme weight |
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| 25. |
Look at the following diagram: 
With reference to the above circuit, a high-value bleed-resistor has been permanently connected across capacitor C1 to:
| A. |
make sure the capacitor changes at a very fast rate |
| B. |
keep the charge time of the capacitor to one time constant |
| C. |
allow for the failure of the charging resistor R1 during switch-off |
| D. |
ensure a controlled discharge when the supply is disconnected |
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| 26. |
If an oil-filled capacitor has less than its rated capacitance then the most likely cause would be that:
| A. |
some of the oil has leaked out |
| B. |
the electrolyte has dried out |
| C. |
it needs recharging on an AC supply |
| D. |
the supply voltage has a DC component |
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| 27. |
To test a large capacitor, an ohm-meter is placed across the terminals of a known discharged capacitor. If there is capacity in the capacitor the resistance will be:
| A. |
high at first but decreasing |
| B. |
low at first but increasing |
| C. |
constant at all ranges of the ohm-meter |
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| 28. |
Look at the following diagram: 
The capacitors shown are:
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