CBSE Class 12 · 2013 · EM WavesVery Short Answer

WhatsApp Email

Welders wear special goggles or face masks with glass windows to protect their eyes from certain electromagnetic radiations. Name these radiations and write the range of their frequency.

Answer: Ultraviolet (UV) rays; frequency range about $7.5 \times 1 0^{14}$ Hz to $3 \times 1 0^{16}$ Hz.

Solution

The intense welding arc emits strong ultraviolet radiation, which can damage the eyes; the goggles absorb it.
Ultraviolet rays span roughly

λ = 400

nm down to about

1

nm, i.e. a frequency range of about

7.5 \times 1 0^{14}

Hz to

3 \times 1 0^{16}

Hz.

UV rays, \sim 1 0^{15} - 1 0^{16} Hz

CBSE Class 12 Board · 2013 · Subjective

Practise more: all CBSE board PYQs on EM Waves →

More board questions on EM Waves

The electromagnetic waves used to purify water are
CBSE 2024View solution →
Name the parts of the electromagnetic spectrum which are
(i) stopped by the face mask worn by welders,
(ii) used in the detectors in Earth satellites, and
(iii) used in the 'short-wave band' in communication. Also write the order of wavelengths in each case.
CBSE 2024View solution →
$E$ and $B$ represent the electric and magnetic fields of an electromagnetic wave respectively. The direction of propagation of the wave is along
CBSE 2023View solution →
How are infrared waves produced? Why are these waves referred to as heat waves? Give any two uses of infrared waves.
CBSE 2023View solution →
(a) (i) Arrange the following electromagnetic radiations in the ascending order of their frequencies: X-rays, microwaves, gamma rays, radio waves.
(ii) Write two uses of any two of these radiations.
CBSE 2022View solution →
(a) Write the expression for the speed of light in a material medium of relative permittivity $ε_{r}$ and relative magnetic permeability $μ_{r}$ .
(b) Write the wavelength range and name of the electromagnetic waves which are used in (i) radar systems for aircraft navigati …
CBSE 2020View solution →