Calculating with electric charge: including complex calculations
I can explain the equations: I = Q ÷ t, V = E ÷ Q, P = I × V, and V = I × R, and use them in calculations.
Calculating with electric charge: including complex calculations
I can explain the equations: I = Q ÷ t, V = E ÷ Q, P = I × V, and V = I × R, and use them in calculations.
Lesson details
Key learning points
- Electric charge, Q, is measured in coulombs (C).
- Electric current is a measure of the rate of flow of electric charge, calculated using: I = Q ÷ t.
- Potential difference is a measure of the energy transferred by each coulomb of charge, calculated using: V = E ÷ Q.
- Combining I = Q ÷ t and V = E ÷ Q gives the equation: E ÷ t = I × V. This is equivalent to P = I × V.
- Unknown variables in the power equation can often be calculated using: I = V ÷ R.
Common misconception
Understanding electrical circuits is about memorising equations and procedures.
Give pupils the opportunity to discuss what happens in a circuit before they attempt to answer questions about it.
Keywords
Electric current - an electrical property; it can either be positive or negative
Coulombs (C) - the unit of electric charge
Electric current - the amount of electric charge flowing past a point in a circuit each second
Potential difference (p.d.) - the amount of energy transferred by each coulomb of charge, passing between two points in a circuit
Power - the amount of energy transferred each second
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Video
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Starter quiz
6 Questions
current -
charge flowing past a point in a circuit per second
electric charge -
a property that can either be positive or negative
potential difference -
energy transferred per unit charge passing between two points
current -
A
energy -
J
potential difference -
V
power -
W
Exit quiz
6 Questions
$$E$$ -
J
$$I$$ -
A
$$P$$ -
W
$$Q$$ -
C
$$t$$ -
s
$$V$$ -
V