The potential difference between the terminals of an electric heater is `60 V` when it draws a current of `4 A` from the source. What current will the heater draw if the potential difference is increased to `120 V` ?

Answer

`8 A`

Explanation

Resistance of the electric heater , `R = (V)/(I) = (60 V)/(4 A) = 15 Omega`
Changed pd, i.e., `V' = 120 V`
Changed current, i.e., `I' = (V')/( R) = (120 V)/(15 Omega) = 8 A`
Aliter. Since `R` remains the same, by doubling the pd (from 60 V to 120 V), the current is also doubled i.e., becomes `8 A` (as `I` prop V).