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Question
Name two electromagnetic waves of frequency smaller than that of violet light. State one use of each.
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Solution
1) Ultraviolet radiations - 100 Å to 4000 Å
Use: For detecting purity of gems, eggs, ghee, etc.
2) X-rays - 0.1 Å to 100 Å
Use: For detecting fracture in bones, teeth, etc.
RELATED QUESTIONS
Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs.
(a) 21 cm (wavelength emitted by atomic hydrogen in interstellar space).
(b) 1057 MHz (frequency of radiation arising from two close energy levels in hydrogen; known as Lamb shift).
(c) 2.7 K [temperature associated with the isotropic radiation filling all space-thought to be a relic of the ‘big-bang’ origin of the universe].
(d) 5890 Å - 5896 Å [double lines of sodium]
(e) 14.4 keV [energy of a particular transition in 57Fe nucleus associated with a famous high resolution spectroscopic method (Mössbauer spectroscopy)].
X-ray from a Coolidge tube is incident on a thin aluminium foil. The intensity of the X-ray transmitted by the foil is found to be I0. The heating current is increased to increase the temperature of the filament. The intensity of the X-ray transmitted by the foil will be
(a) zero
(b) < I0
(c) I0
(d) > I0
A free atom of iron emits Kα X-rays of energy 6.4 keV. Calculate the recoil kinetic energy of the atom. Mass of an iron atom = 9.3 × 10−26 kg.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
Name the scientist who discovered Microwaves
Name two sources of ultraviolet radiation.
Give one use of electromagnetic radiation in Microwaves.
Answer briefly.
Why light waves travel in a vacuum whereas sound waves cannot?
Photons of an electromagnetic radiation has an energy 11 keV each. To which region of electromagnetic spectrum does it belong?
Choose the correct option related to wavelengths (λ) of different parts of the electromagnetic spectrum.
What is the speed of radio waves in vacuum?
