Capacitors
Physics · 50 practice questions
Types and functions of capacitors; parallel plate capacitors; capacitance and the factors affecting it (area, plate separation, medium, C = εA/d); capacitors in series and parallel; energy stored in a capacitor.
- Determine uses of capacitors and analyse parallel plate capacitors.
- Determine the capacitance of a capacitor and the factors affecting it.
- Solve problems involving series/parallel arrangements and the energy stored in capacitors.
Try a few questions
- Practice question 1
The smaller the separation between a capacitor's plates, the greater its capacitance, since the electric field becomes
- A.weaker for the same voltage, reducing its ability to store charge
- B.stronger for the same voltage, improving its ability to store charge
- C.completely unrelated to the plate separation
- D.identical regardless of the plate separation used
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B. stronger for the same voltage, improving its ability to store charge
A smaller gap concentrates the electric field more strongly for a given voltage, allowing more charge to be stored.
- Practice question 2
A variable capacitor, commonly used for tuning radio circuits, typically has its capacitance adjusted by
- A.changing the electrical charge stored on its plates directly
- B.changing the overlapping area between its plates
- C.changing the frequency of the connected power supply
- D.changing the colour of its plates
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B. changing the overlapping area between its plates
Rotating one set of plates relative to another varies the overlapping area, and hence the capacitance, in these devices.
- Practice question 3
Capacitors used in camera flash units must be capable of releasing their stored energy very rapidly, requiring
- A.a very high internal resistance path to the flash bulb
- B.no electrical connection at all to the flash bulb
- C.a low internal resistance path to the flash bulb
- D.a very slow, gradual discharge over several seconds
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C. a low internal resistance path to the flash bulb
A low-resistance discharge path allows the capacitor's stored energy to be released almost instantly, producing the camera's brief, bright flash.
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