The region of the atmosphere above the troposphere is known as:

Which of the following rays has the maximum frequency?

How are infrared waves produced?

What is an ozone hole?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R.$
Assertion $A:$ $EM$ waves used for optical communication have longer wavelengths than that of microwaves employed in $RADAR$ technology.
Reason $R:$ Infrared $EM$ waves are more energetic than microwaves (used in $RADAR$).
In the light of the given statements,choose the correct answer from the options given below:

The magnetic field in a plane electromagnetic wave is given by $B = 2 \times 10^{-7} \sin(0.5 \times 10^3 x + 1.5 \times 10^{11} t)$. This electromagnetic wave is .........