13 April 2015
6.5 Electrical Energy and
Charge
How many meanings of the word
charge can you think of?
6.5 Electrical Energy and Charge
13 April 2015
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