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?

The electromagnetic waves of frequency $2 \ MHz$ to $30 \ MHz$ are used in:

In the following,List $A$ consists of the wavelength range of different $EM$ waves and List $B$ consists of ways to produce them. Match the following lists.
| List $A$ | List $B$ |
| :--- | :--- |
| $A$. $400 \ nm$ to $1 \ nm$ | $1$. Radioactive decay of the nucleus. |
| $B$. $> 0.1 \ nm$ | $2$. Vibration of atoms and molecules. |
| $C$. $1 \ mm$ to $700 \ nm$ | $3$. Rapid acceleration and deceleration of electrons in aerials. |
| $D$. $< 10^{-3} \ nm$ | $4$. Inner shell electrons in atoms moving from one energy level to a lower level. |

Which of the following is not an electromagnetic wave?

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

$A$ monochromatic source of light operating at $15 \text{ kW}$ emits $2.5 \times 10^{22} \text{ photons/s}$. The region of an electromagnetic spectrum to which the emitted electromagnetic radiation belongs to . . . . . . . (Take $h = 6.6 \times 10^{-34} \text{ J}\cdot\text{s}$ and $c = 3 \times 10^8 \text{ m/s}$).