Download 6.4 Electrical Power and Potential Difference.

23 May 2017
6.5 Electrical Energy and
Charge
How many meanings of the word
charge can you think of?
6.5 Electrical Energy and Charge
23 May 2017
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