Heating Effect of Electricity and Joule law

< <Heating Effect of

Electricity

< <

Why 100W bulb produces more heat than CFL?

Electric Power(W) = Voltage(V) x Current(I)

100W30W10W

< < Electric Power(W) = Voltage(V) x Current(I)


More power means as more current required

< < Q I2

Heat produced is directly proportional to the square of electric current. So, electric current means more heat.

Produced heat

Current flow

< < Q I2

Produced heat

Current flow

Assuming Resistance is unchanged

< <

Electric Power(W) = Voltage(V) x Current(I)


More current means more heat

Q I2

< < Q/I2 = constant

Q I2

< < Q/I2 = constant

I is doubled Q/(2I)2 = constant

< < Q/I2 = constant

I is doubled Q/(2I)2 = constant

Q =4I2xconstantQ would increase 4 times

Q R

Resistance of conductor

More resistance means more heat

High resistance material

Q R



Heat produced is directly proportional to resistance of

conductor

Q R


Q R



Heat produced is directly proportional to resistance of

conductor

Q R


Assuming current is unchanged

Q I2 R

Joule heating

Nichrome with high R and high current (I) produces

heat in this heater

Nichrome coil

Heating Effect of Electricity and Joule law

Engineering

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