Question

A typical wavelength oven operates at 2.45 GHz. Calculate the wavelength of this electromagnetic radiation. How does this compare to the width of a typical microwave (the one in your home is about 30 cm wide)? Assuming the waves are a standing wave, how many nodes are in the microwave? Have you ever observed phenomenon?

Answer 1

f = 2.45 GHZ = 2.45*10^9 Hz

wavelength = c /f
     = 3*10^8 / 2.45*10^9
     = 0.122 m
     =12.2 cm
Answer: wavelength = 12.2 cm

It is less than width of typical microwave.
Width of microwave is approximately 2.5 times the wavelength

Assuming fundamental standing wave is formed.
Number of waves in microoven = 30 cm / 12.2 cm = 2.5 approx
So number of nodes =6
source:http://www.physicsclassroom.com/class/sound/Lesson-4/Fundamental-Frequency-and-Harmonics

We might have observed this phenomena when we hear echo in closed room. We hear the same voice multiple times due to nodes formation