Advertisements
Advertisements
प्रश्न
Answer briefly.
Why light waves travel in a vacuum whereas sound waves cannot?
उत्तर
Light waves are electromagnetic waves that can travel in a vacuum where sound waves travel due to the vibration of particles of the medium. Without any particles present (like in a vacuum) no vibrations can be produced. Hence, the sound wave cannot travel through the vacuum.
APPEARS IN
संबंधित प्रश्न
If the earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain.
If the earth did not have an atmosphere, would its average surface temperature be higher or lower than what it is now?
State Moseley's law
A wave has a wavelength of 10-3 nm. Name the wave.
What is the range of the wavelength of the following electromagnetic waves?
(a) Gamma rays.
Name the radiations of wavelength just shorter than 4 × 10-7 m.
Give one use of gamma rays.
Name three properties of ultraviolet radiations which are similar to visible light.
If the potential difference applied to the tube is doubled and the separation between the filament and the target is also doubled, the cutoff wavelength
The X-ray beam emerging from an X-ray tube
The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiation,
(a) the intensity increases
(b) the minimum wavelength increases
(c) the intensity remains unchanged
(d) the minimum wavelength decreases.
X-ray incident on a material
(a) exerts a force on it
(b) transfers energy to it
(c) transfers momentum to it
(d) transfers impulse to it.
The Kβ X-rays from certain elements are given below. Draw a Moseley-type plot of √v versus Z for Kβ radiation.
Element | Ne | P | Ca | Mn | Zn | Br |
Energy (keV) | 0.858 | 2.14 | 4.02 | 6.51 | 9.57 | 13.3 |
If the operating potential in an X-ray tube is increased by 1%, by what percentage does the cutoff wavelength decrease?
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
-
- Calculate the speed of the wave.
- Name the medium through which it is traveling.
Name three radiations and their wavelength range which are invisible and beyond the violet end of the visible spectrum.
Name the part of the electromagnetic spectrum which is:
Produced by bombarding a metal target with high electrons.
Calculate the shortest wavelength of electromagnetic radiation present in Balmer series of hydrogen spectrum.
Define the term "Intensity" in the photon picture of electromagnetic radiation.
Answer the following question.
Gamma rays and radio waves travel with the same velocity in free space. Distinguish between them in terms of their origin and the main application.
How will you investigate the existence of the radiation beyond the red and violet extremes of the spectrum?
State two properties of infrared radiations which differ from visible light.
Choose the correct option.
Earth’s atmosphere is richest in
An e.m. wave exerts pressure on the surface on which it is incident. Justify.
Following QN ∴ 14, the radiation force on the roof will be
The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is ______.
Arrange the following electromagnetic radiation in the ascending order of their frequencies:
X-rays, microwaves, gamma rays, radio waves
Which one of the following electromagnetic radiation has the least wavelength?
Identify the electromagnetic wave whose wavelength range is from about 10-3 m to about 10-1 m. Write one use of this.