Heating Effect of a Current
When electrons pass through a wire, they give some of their energy to the atoms in the wire and make them vibrate more and as a result the wire gets hot.
To see applications of the heating effect of a current Click here |
A coiled heating element from an electric toaster |
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The Filament Lamp
Electrical Power
Power is the rate at which work is done OR the rate at which energy is being supplied or converted.
POWER = WORK DONE
TIME TAKEN
TIME TAKEN
Energy transferred = p.d x current x time
Energy transferred = p.d x current
time
From the definition of Power we have:
POWER = CURRENT x POTENTIAL DIFFERENCE
P = I x V
Also,
Energy transferred = p.d x current
time
From the definition of Power we have:
POWER = CURRENT x POTENTIAL DIFFERENCE
P = I x V
Also,
Worksheet
1.How much energy does a 60W bulb convert in 1 hour?
How much current flows through the 60W bulb when it is operated from a 120V source?
2.A 500W element of a 240V stove is switched on for 1 hour.
(i) How much energy does the element convert in 1 hour?
(ii) What is the current in the element?
3.An electric kettle connected to the 230V mains supply draws a current of 10A.
Calculate
(a) the power of the kettle.
(b) the energy transferred in 1 minute.
How much current flows through the 60W bulb when it is operated from a 120V source?
2.A 500W element of a 240V stove is switched on for 1 hour.
(i) How much energy does the element convert in 1 hour?
(ii) What is the current in the element?
3.An electric kettle connected to the 230V mains supply draws a current of 10A.
Calculate
(a) the power of the kettle.
(b) the energy transferred in 1 minute.