Microwave Oven

Microwaves

Raghav bought 25 washing machines and microwave ovens for Rs. 2,05,000. He sold 80% of the washing machines and 12 microwave ovens for a profit of Rs. 40,000. Each washing machine was marked up by 20% over cost and each microwave oven was sold at a profit of Rs. 2,000. The remaining washing machines and 3 microwave ovens could not be sold. What is Raghav’s overall profit/loss?

A : If dipole moment of water molecules were zero, then microwave cooking would not be possible. R : In a microwave oven the water molecules vibrate due to oscillating electric field in microwave and heat the food.

A microwave oven operates at 2.5 GHz. Assume that 5% of microwave photons are absorbed by 200 ml of water kept inside the oven. The time needed to warm the water from 20^(@)C to 70^(@)C is 2 minute. Specific heat capacity of water is 4.2 Jg^(–1) .^(@)C^(–1) . Neglect any heat loss by water to the surrounding. Calculate the number of photons emitted per second per kilowatt of power consumed by the microwave. Efficiency of the oven to convent electrical energy into microwave energy is 70%