Question

What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.

Answer 1

Joule's law of heating states that heat produced in the resistor is 

1. directly proportional to the square of the current.
2. directly proportional to the resistance.
3. directly proportional to the current.

Mathematically, 

H = i²Rt

where, 
H = Heat produced
I = Current
R = Resistance
t = time

Experimental demonstration

1. Take a water heating immersion rod, water, bucket, thermometer, regulator.
2. Immerse the water heating immersion rod in the water and measure the time taken to heat the water upto a certain temperature.
3. Now increase the current to double with the help of regulator and now measure the time taken to heat the water upto the same temperature.
   Then, we will observe that time taken in second case will be one fourth the time taken in earlier case. Hence, it verifies the Joule's law of heating.
   
   Electric fuse, toaster, oven, kettle, are the four applications of Joule's law of heating in daily life.