Question

A $ 30^{0}C $ rise of temperature is observed in a conductor by passing a certain current. When the current is doubled ,the rise of temperature will be
(A) $ 150^{0}C $
(B) $ 120^{0}C $
(C) $ 90^{0}C $
(D) $ 30^{0}C $

Answer 1

Hint
Temperature affects how electricity flows through an electrical circuit by changing the speed at which the electrons travel. This is due to an increase in resistance of the circuit that results from an increase in temperature. Likewise, resistance is decreased with decreasing temperatures.

Complete step by step answer
The initial temperature is $ 30^{0}C $ .
We know the relation between heat and current flow is,
 $ H = {i^2}Rt $
Here, Rt = constant
So we can say, $ H\,\alpha \,{i^2} $
So, when the current i is double, heat will be four times increased.
As heat is proportional to change in temperature
 $ \therefore H\,\alpha \,\Delta T $
So, the rise of temperature is = 3 × 4 = $ 120^{0}C $.
Option (B) is correct.

Note
Heat is the form of energy that is transferred between systems or objects with different temperatures (flowing from the high-temperature system to the low-temperature system). Also referred to as heat energy or thermal energy. Heat is typically measured in Btu, calories or joules. Heat is transferred via solid material (conduction), liquids and gases (convection), and electromagnetic waves (radiation). Heat is usually transferred in a combination of these three types and seldom occurs on its own.