6.5 Electrical Energy and Charge

April 18, 2023

How many meanings of the word charge can you think of?

6.5 Electrical Energy and Charge

April 18, 2023

Page 192 AQA Physics

• What is electric current?• What is the unit of electric charge?• What energy changes take place

when charge flows through a resistor?

What is electric current?

Conventional current electrons

Conventional current

In metals current is a flow of electrons. In all materials current is a flow of charged particles.

What is the unit of charge?

• Charge is measured in Coulombs, C.• Charge flow = current x time

(Coulombs) (Amperes) (seconds)

E.g. A flow of 2A for 5s is a charge of 10 Coulombs.Page 192 Q a)

The capacity store of a battery is shown as Amp-hours or milliamp-hours (mAh). This tells you how long a battery can deliver a certain current.

Energy and potential difference

Energy transformed = potential difference x charge flow

From page 193 copy the worked example and answer b).

Summary

• An electric current is a flow of charge.

• When charge flows through a resistor, electrical energy is transferred as heat.

• Charge = Current x time• Energy transferred = pd x time