In a microwave oven,which type of waves are used?

If an electron oscillates at a frequency of $1 \, GHz$,it emits:

Arrange the following in the ascending order of wavelength $(\lambda) :$
$(A)$ Microwaves $(\lambda_1)$
$(B)$ Ultraviolet rays $(\lambda_2)$
$(C)$ Infrared rays $(\lambda_3)$
$(D)$ $X-$rays $(\lambda_4)$
Choose the most appropriate answer from the options given below $:-$

Which of the following electromagnetic waves have the minimum frequency?

$A$ charged particle oscillates about its mean equilibrium position with a frequency of $10^9 \ Hz$. The electromagnetic waves produced:

Cellular phones use radio waves to transmit voice communication in the . . . . . . band.