c = fl

where

c = speed of electromagnetic radiation = 3 x 10⁸ m/s

f = frequency of the waves = 2.45 GHz = 2.45 x 109 Hz

l = wavelength of the microwaves

l = c/f

= 3 x 10⁸ / 2.45 x 10⁹

= 0.12 m or 12 cm ANS