Capacitors Tut 1

(Click the question to get the answer.)

1. Describe the structure of a capacitor.
A capacitor is made up of two conducting sheets. The sheets are placed very close to each other. An insulator (called a dielectric) is placed between the sheets so that the sheets do not make electrical contact with each other.

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2. What is an insulator?
a material that does not electrical current to flow through it
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3. What is the the name for the insulator in a capacitor?
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4. What is the purpose of a capacitor?
It can store a large amount of charge, and release it very quickly. This would be very useful especially for a camera flash, or a shock-stick.
It usually takes a little longer to fully charge a capacitor with charge, but it can release the charge very quickly.
It takes a while to blow a balloon with air, but the balloon can release all that air very fast when burst!

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5. What is the symbol for a capacitor?
two lines of equal length

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6. Draw a simple circuit diagram showing one capacitor connected in series to a battery.

Electrons from the battery will collect on the plate, and the plate becomes negative.
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7. What happens to the rate of flow of charge from the battery as the capacitor is being charged (filled up)?
The rate of flow of charge from the battery through the circuit decreases progressively.

This is because as the plate of the capacitor becomes more and more "filled" with negative charge (electrons), this very plate provides more and more opposition to new approaching electrons from the battery.
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8. Why is a capacitor similar to a battery?
It can provide electrical energy to another device.
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9. Does a capacitor store or create electrons?
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10. Where does a capacitor store the electrical energy?
in the electric field between the plates
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11. Describe the electric field between the plates.
The electric field is uniform, which means that:
• it is of constant magnitude
• and constant direction
It is exactly the same anywhere between the plates, not stronger nearer a plate.
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12. Why can a capacitor be regarded as environmentally friendly?
A capacitor does not contain any harmful chemicals that can damage the environment.
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