Question

A cube of water 11 cm on a side is placed in a microwave beam having E0 = 15 kV/m . The microwaves illuminate one face of the cube, and the water absorbs 74 % of the incident energy.

How long will it take to raise the water temperature by 50 ∘C

? Assume that the water has no heat loss during this time.

Answer 1

Given that,

One side of cube = 11 cm

Intensity of electric field = 15 kV/m

Absorption=74%

Suppose How long will it take to raise the water temperature by 50°C Assume that the water has no heat loss during this time.

We need to calculate the rate of energy transfer from the beam to the cube

Using formula of rate of energy

We need to calculate the amount of heat

Using formula of heat

We need to calculate the time

Using formula of time

​​​​​​

Hence, The time is 4272.2 sec.