A microwave oven has conducting walls that form a cavity of dimensions 37cm× 48.

Question

A microwave oven has conducting walls that form a cavity of dimensions 37cm×  48.8cm×20cm. When 2.45-GHz microwaves are continuously introduced into this cavity, reflection of incident waves from the walls set up standing waves. Since the electric field must be zero inside a conductor, the standing waves have nodes at the walls. This frequency of microwave is efficiently absorbed by water molecules in food or beverages, providing effective heat transfer.

Part B:  What is the distance between adjacent nodes?

Explanation / Answer

Given that the frequency of the micro wave oven is, f = 2.45 GHz = 2.45*109 Hz

length = 37 cm = 0.37m

Part-A

wave length of the wave is, lambda = c / f

lambda = 3*108 / 2.45*109 = 0.1224 m

total number of loops is given by,

n = 2*l / lambda = 2*0.37 / 0.1224

n = 6

So, the total number of loops will be, m = n - 1 = 6 - 1

the total number of loops will be, m = 5.

Part-B

distance between adjacent nodes is given by,

d = l / n

d = 0.37 / 6

d = 6.1 cm

distance between adjacent nodes is 6.1 cm

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