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प्रश्न
Answer briefly.
Can we produce a pure electric or magnetic wave in space? Why?
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उत्तर
No.
In vacuum, an electric field cannot directly induce another electric field so a “pure” electric field wave cannot exist and same can be said for a “pure” magnetic wave.
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संबंधित प्रश्न
Identify the part of the electromagnetic spectrum which is suitable for radar system used in aircraft navigation.
The terminology of different parts of the electromagnetic spectrum is given in the text. Use the formula E = hv (for energy of a quantum of radiation: photon) and obtain the photon energy in units of eV for different parts of the electromagnetic spectrum. In what way are the different scales of photon energies that you obtain related to the sources of electromagnetic radiation?
The wavelengths for the light of red and blue colours are roughly 7.8 × `10^7` m and 4.8 × `10^7` m respectively.
(a) Which colour has the greater speed in vacuum?
(b) Which colour has the greater speed in glass?
What is the range of the wavelength of the following electromagnetic waves?
(a)X-rays,
Name the waves used for taking photographs in dark.
Two waves A and B have wavelength 0.01 Å and 9000 Å respectively.
- Name the two waves.
- Compare the speeds of these waves when they travel in vacuum.
Name two sources, each of infrared radiations and ultraviolet radiations.
Name of physical quantity which remains same for microwaves of wavelength 1 mm and UV radiations of 1600 Å in vacuum.
The energy of a photon of a characteristic X-ray from a Coolidge tube comes from
50% of the X-rays coming from a Coolidge tube are able to pass through a 0.1 mm thick aluminium foil. If the potential difference between the target and the filament is increased, the fraction of the X-rays passing through the same foil 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.
What potential difference should be applied across an X-ray tube to get X-ray of wavelength not less than 0.10 nm? What is the maximum energy of a photon of this X-ray in joule?
(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.
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.)
Answer briefly.
What are radio waves?
Answer briefly.
Give two uses of radio waves.
Answer briefly.
Why high-frequency carrier waves are used for the transmission of audio signals?
Name the e.m. waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves.
An e.m. wave exerts pressure on the surface on which it is incident. Justify.
Radio waves of constant amplitude can be generated with.
SONAR emits which of the following waves?
What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of a room, its intensity essentially remains constant. What geometrical characteristic of LASER beam is responsible for the constant intensity which is missing in the case of light from the bulb?
Give any two uses of infrared waves.
Name the electromagnetic radiation whose frequency is 10 Hz.
Name one radiation having the wavelength longer than the wavelength of these radiations.
Name two electromagnetic waves of wavelength smaller than that of violet light.
What do electromagnetic waves require for propagation?
How do the wavelengths and frequencies of microwaves compare with those of radio waves?
How does the frequency of infrared radiation compare with that of microwaves?
