Wave Nature of Electromagnetic Radiation

Arrange the following type of radiations in increasing order of frequency:

1. radiation from microwave oven
2. amber light from traffic signal
3. radiation from FM radio
4. cosmic rays from outer space and
5. X-rays.

Neon gas is generally used in the signboards. If it emits strongly at 616 nm, calculate

1. the frequency of emission,
2. distance traveled by this radiation in 30 s
3. energy of quantum and
4. number of quanta present if it produces 2 J of energy.

Calculate the wavelength, frequency and wave number of a light wave whose period is 2.0 × 10^-10s.

Chlorophyll present in green leaves of plants absorbs light at 4.620 × 10¹⁴ Hz. Calculate the wavelength of radiation in nanometer. Which part of the electromagnetic spectrum does it belong to?

Nitrogen laser produces radiation at a wavelength of 337.1 nm. If the number of photons emitted is 5.6 × 10²⁴, calculate the power of this laser.

Threshold frequency, ν₀ is the minimum frequency which a photon must possess to eject an electron from a metal. It is different for different metals. When a photon of frequency 1.0 × 10¹⁵ s^–1 was allowed to hit a metal surface, an electron having 1.988 × 10^–19 J of kinetic energy was emitted. Calculate the threshold frequency of this metal. Show that an electron will not be emitted if a photon with a wavelength equal to 600 nm hits the metal surface.

The Balmer series in the hydrogen spectrum corresponds to the transition from n₁ = 2 to n₂ = 3, 4,.......... This series lies in the visible region. Calculate the wave number of line associated with the transition in Balmer series when the electron moves to n = 4 orbit. (R_H = 109677 cm^–1)

Assertion (A): Black body is an ideal body that emits and absorbs radiations of all frequencies.

Reason (R): The frequency of radiation emitted by a body goes from a lower frequency to higher frequency with an increase in temperature.