Page 152 - Knowledge Organiser Yr9 24-25

Knowledge Base: Science P2: Electricity Year 9
8. Power
Worked examples
8.1 Define power.
Energy transferred per second
8.13 An electric toaster is powered by the mains supply at 230V. is supplied to
the toaster, calculate its power.
8.2
State the equation linking current, potential difference and power using words.
What symbol is used instead of writing the word "power"?
8.5 State the unit of power.
Watts or W
8.15 A small fan is run from a computer's USB port. It has a
W and draws a A. Calculate its
resistance.
Power = current x potential difference
P= V x I
P
6.5A of current
8.3
State the equation linking current, potential difference and power using symbols.
8.14
A 75W ceiling fan is powered by the mains supply at 230V, calculate the current supplied to the fan.
8.4
8.6
State the equation linking current, resistance and power using words.
Power = current2 x resistance
power of 2.5
current of 0.5
8.7
State the equation linking current, resistance and power using symbols.
P= I2 x R
8.8
What 2 factors determine the amount of energy transferred by an appliance?
Power of the appliance and time it is on.
8.16
A child is playing with a battery powered toy car. She turns it on for 20 seconds. The power of the car is 50W, calculate the energy transferred.
8.9
State the equation linking time, energy and power using words.
Energy = power x time
8.10
State the equation linking time, energy and power using symbols.
E = Px t
8.11
State the equation linking Energy, Charge flow and potential difference using words
8.17
A mobile phone charger has a V. If are transferred,
calculate the charge flow.
Energy = Charge flow x potential difference
potential difference of 12
3kJ of energy
8.12
State the equation linking Energy, Charge flow and potential difference using words
E= Q x V
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