Tag: electromagnetic waves

Questions Related to electromagnetic waves

For an electromagnetic radiation,

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. only momentum is quantised

  2. only energy is quantised

  3. both energy and momentum are
    quantised

  4. neither of them is quantised

Show answer
Correct Option: A
Explanation:

For an electromagnetic radiation, only momentum is quantised$.$

Hence,
option $(A)$ is correct answer.

If a source of power $4$ kW produces $10^{26}$ photons/second, the radiation belongs to a part of the spectrum called:

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. X-rays

  2. Ultraviolet rays

  3. Microwaves

  4. $\gamma$-rays

Show answer
Correct Option: C
Explanation:
$4000 \ J$ of energy is produced from $10^{26}$ photons in one second.
Energy of each photon   $E = \dfrac{4000}{10^{26}} = 4\times 10^{-23} \ J$
Frequency of each photon   $\nu = \dfrac{E}{h} = \dfrac{4\times 10^{-23}}{6.63\times 10^{-34}} = 6\times 10^{10} \ Hz$
So the radiation belongs to micro waves.
Correct answer is option C.