Question

An electric heater working on 200volt DC main raises the temperature of 100g of water at 20°c to boiling point in 30 s what is resistance of heater?​

Answer 1

Answer:

The total electrical energy supplied to boil water in the kettle is W = VIt

Since nothing is clearly mentioned about the source of electrical power,

we assume that the power source is the same, that means the electrical energy obtained from the power source is the same,

i.e the current is same.

Current is same

R is the resistance of the coil in the electric kettle.

Electric kettle

We have to calculate t

The time t taken to boil the same amount of water for 120 V

supply is equal to

Time taken to boil the water

Solving this equation we get, t = 1008.33s = 16.8 minutes.