Infrared radiation was discovered in $1800$ by

If a source of $4 \ kW$ power emits $10^{20}$ photons/second,then this radiation belongs to which part of the electromagnetic spectrum?

If $\lambda_r$,$\lambda_v$,and $\lambda_x$ are the wavelengths of red light,violet light,and $X$-rays respectively,then which of the following relations is correct?

Which electromagnetic waves are used in the medical field to destroy cancer cells?

Which of the following is responsible for the greenhouse effect?

Match the electromagnetic radiations given in List-$I$ with their uses given in List-$II$.
| List-$I$ | List-$II$ |
| :--- | :--- |
| $A$) $X$-rays | $P$) Remote switches |
| $B$) $UV$-rays | $Q$) Finger prints in forensic labs |
| $C$) Radio waves | $R$) Crystal structure study |
| $D$) $IR$-rays | $S$) $TV$ communication system |