23.2- ENERGY STORED IN A CHARGED CAPACITOR

Question 1

When a capacitor is charged, why is energy stored in it?

Answer 1

as electrons forced onto one of its plates + taken off the other plate

Question 2

How is charge stored in a capacitor?

Answer 2

as electrical potential energy

Question 3

What will a charged capacitor discharged across a torch bulb do?

Answer 3

release its energy in a brief flash of light from the bulb, as long as the capacitor has first been charged to operating pd of bulb

Question 4

Equation for energy stored by capacitor?

Answer 4

E = 1/2QV

Question 5

What can be used to measure the energy transfer from a charge capacitor to a light bulb when the capacitor discharges?

Answer 5

joulemeter

Question 6

How is a joulemeter used to measure the energy transfer from a charged capacitor to a light bulb when the capacitor discharges?

Answer 6

before the discharge starts, capacitor pd measured + joulemeter reading recorded
when capacitor discharged, joulemeter reading recorded again
difference between two joulemeter readings is energy transferred from capacitor during discharge process

Question 7

Equation for energy stored in thundercloud?

Answer 7

E = 1/2QEd

E- electrical field strength
d- height of thundercloud above ground

Question 8

Why does energy stored increase when a thundercloud rises to a new height?

Answer 8

as work done by force of wind

it has to overcome electrical attraction between thundercloud + ground to make thundercloud move away from ground

Question 9

When does the insulating propertu of air break down?

Answer 9

if it’s subjected to an electric field stronger than about 300kVm-1