Advertisements
Advertisements
प्रश्न
The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is ______.
विकल्प
`c : 1`
`c^2 : 1`
`1 : 1`
`sqrt(c) : 1`
Advertisements
उत्तर
The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is 1 : 1.
Explanation:
Average energy by electric field E0 is Uav
`U_(av) = 1/2 ε_0 E_0^2`
But E0 = cB0
(Uav) electric field = `1/2 ε_0 (cB_0)^2 = 1/2 ε_0c^2B_0^2`
= `1/2 ε_0* 1/(mu_0ε_0) (B_0)^2` ......`[because c^2 = 1/(mu_0ε_0)]`
(Uav) electric field = `1/(2mu_0) B_0^2 (U_(av))_("magnetic field")`
Ratio = `((U_(av))_("electric field"))/((U_(av))_("magnetic field")) = 1/1`, i.e., 1:1
Hence the energy in electromagnetic wave is divided equally between electric field vector and magnetic field vector.
It means the ratio of contributions by the electric field and magnetic field components to the intensity of an electromagnetic wave is 1:1.
- When the incident EM wave is completely absorbed by a surface, it delivers energy u and momentum u/c to the surface.
- When a wave of energy u is totally reflected from the surface, the momentum delivered to surface is 2u/c.
APPEARS IN
संबंधित प्रश्न
Name the parts of the electromagnetic spectrum which is
used to treat muscular strain.
Write in brief, how these waves can be produced.
A plane electromagnetic wave travels in vacuum along z-direction. What can you say about the directions of its electric and magnetic field vectors? If the frequency of the wave is 30 MHz, what is its wavelength?
State Moseley's law
Name the subjective property of light related to its wavelength.
Name the waves used for taking photographs in dark.
Name three properties of ultraviolet radiations which are similar to visible light.
If the current in the circuit for heating the filament is increased, the cutoff wavelength
Visible light passing through a circular hole forms a diffraction disc of radius 0.1 mm on a screen. If an X-ray is passed through the same setup, the radius of the diffraction disc will be
Cutoff wavelength of X-rays coming from a Coolidge tube depends on the
(a) target material
(b) accelerating voltage
(c) separation between the target and the filament
(d) temperature of the filament.
The wavelength of Kα X-ray of tungsten is 21.3 pm. It takes 11.3 keV to knock out an electron from the L shell of a tungsten atom. What should be the minimum accelerating voltage across an X-ray tube having tungsten target which allows production of Kα X-ray?
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
The Kα and Kβ X-rays of molybdenum have wavelengths 0.71 A and 0.63 A respectively. Find the wavelength of Lα X-ray of molybdenum.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
Answer briefly.
What is a carrier wave?
Solve the numerical problem.
Calculate the frequency in MHz of a radio wave of wavelength 250 m. Remember that the speed of all EM waves in a vacuum is 3.0 × 108 m/s.
Light of wavelength `3500A` is incident on two metals A and B whose work functions are 3.2 eV and 1.9 eV respectively. Which metal will emit photoelectrons?
A car is moving towards a high cliff. The car driver sounds a horn of frequency f. The reflected sound heard by the driver has a frequency 2f. If v be the velocity of sound, then the velocity of the car, in the same velocity units, will be:
The frequency of e. m waves which is best suited .to observed of radius 3 × 10–4 his of the order of
If λv, λx and λm Am represents the wavelength of visible light, x-ray and microwaves respectively, then ______.
Identify the electromagnetic wave whose wavelength range is from about 10-3 m to about 10-1 m. Write one use of this.
What is the wavelength range of electromagnetic radiation used in radio broadcast?
