Capacitors

Question 1

What is time constant?

Answer 1

The time it takes for the p.d. to decrease by 37% of its original value.

Question 2

What is a capacitor?

Answer 2

A capacitor is an electrical component that stores charge on two separated metallic
plates.

Question 3

What is an insulator?

Answer 3

An insulator, sometimes called a dielectric, is placed between the plates to
prevent the charge from travelling across the gap. The dielectric also increases the capacitance of the device by
polarizing in the electric field therefore increasing the charge stored on the plates.

Question 4

Investigating Capacitor-resistor circuits

Answer 4

To investigate the charge or discharge of a capacitor a circuit with a DC power supply you need , a capacitor, a resistor in series, an ammeter in series and a voltmeter in parallel. Then plot current/voltage on a graph against time to investigate the exponential relationships between the variables current/p.d. with time. The experimental value could then be compared to the theoretical value based on the values of the resistance and
capacitance.