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प्रश्न
Give a reason for the following:
Long-distance radio broadcasts use short-wave bands. Why?
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उत्तर
Long distance radio broadcasts use shortwave bands because only these bands can be refracted by the ionosphere.
संबंधित प्रश्न
What role dose infra-red radiation play in physical therapy?
Name the parts of the electromagnetic spectrum which is
used to treat muscular strain.
Write in brief, how these waves can be produced.
Name the parts of the electromagnetic spectrum which is
used as a diagnostic tool in medicine.
Write in brief, how these waves can be produced.
Optical and radio telescopes are built on the ground but X-ray astronomy is possible only from satellites orbiting the earth. Why?
The small ozone layer on top of the stratosphere is crucial for human survival. Why?
If the earth did not have an atmosphere, would its average surface temperature be higher or lower than what it is now?
What do you understand by the statement, "Electromagnetic waves transport momentum"?
What is the range of the wavelength of the following electromagnetic waves?
(A) Radio waves.
Name the region beyond the red end of the spectrum.
Name the waves produced by the changes in the nucleus of an atom.
Can X-rays be polarised?
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
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.
Iron emits Kα X-ray of energy 6.4 keV. Calculate the times taken by an iron Kα photon to cross through a distance of 3 km.
(Use Planck constant h = 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
The wavelengths of Kα and Lα X-rays of a material are 21.3 pm and 141 pm respectively. Find the wavelength of Kβ X-ray of the material.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
The energy of a silver atom with a vacancy in K shell is 25.31 keV, in L shell is 3.56 keV and in M shell is 0.530 keV higher than the energy of the atom with no vacancy. Find the frequency of Kα, Kβ and Lα X-rays of silver.
(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 Visible light
Name the scientist who discovered Infra-red waves
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.
| Gamma rays | D | C | Visible light | B | A |
The above table shows different parts of the electromagnetic spectrum.
(a) Identify the parts of the spectrum marked as A, B, C and D.
(b) Which of the radiations A or B has the higher frequency?
(c) State two properties which are common to all parts of the electromagnetic spectrum.
(d) Name one source of each of the radiation of electromagnetic spectrum.
(e) Name one detector for each of the radiation.
(f) Name one use of each of the radiation.
-
- Calculate the speed of the wave.
- Name the medium through which it is traveling.
Name the part of the electromagnetic spectrum which is:
Suitable for radar systems used in aircraft navigation.
Define the term "Intensity" in the photon picture of electromagnetic radiation.
Identify the part of the electromagnetic spectrum used in (i) radar and (ii) eye surgery. Write their frequency range.
Name the radiation of the electromagnetic spectrum which is used for the following:
For taking photographs of the sky during the night and foggy conditions . Give the frequency range
State two properties of infrared radiations which differ from visible light.
State three properties of infrared radiations similar to that of visible light.
Give one use of electromagnetic radiations in Infrared radiation.
Name the radiations used for the detection of fracture in bones.
What is the wavelength of the wave whose frequency is 1012 Hz? Name the electromagnetic wave.
Choose the correct option.
How does the frequency of a beam of ultraviolet light change when it travels from air into glass?
Answer briefly.
Can we produce a pure electric or magnetic wave in space? Why?
Name the e.m. waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves.
X-rays, gamma rays and microwaves travelling in a vacuum have ______.
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
Ozone layer above the earth's atmosphere will
Find the photon energy in units of ev for electromagnetic wave if waves length 40 m. Given h = 6.63 × 10–34 J.
The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is ______.
Electromagnetic waves with wavelength
- λ1 is suitable for radar systems used in aircraft navigation.
- λ2 is used to kill germs in water purifiers.
- λ3 is used to improve visibility in runways during fog and mist conditions.
Identify and name the part of the electromagnetic spectrum to which these radiations belong. Also arrange these wavelengths in ascending order of their magnitude.
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.
Name the electromagnetic radiation whose frequency is 10 Hz.
What is the speed of radio waves in vacuum?
What happens when an electron collides with a positron?
What is the wavelength range of electromagnetic radiation used in radio broadcast?
In an atom X, electrons absorb the energy from an external source. This energy “excites” the electrons from a lower-energy level to a higher-energy level around the nucleus of the atom. When electrons return to the ground state, they emit photons.
The figure below is the energy level diagram of atom X with three energy levels, E1 = 0.00eV, E2 = 1.78eV and E3 = 2.95eV. The ground state is considered 0 eV for reference. The transition of electrons takes place between levels E1 and E2.
- What wavelength of radiation is needed to excite the atom to energy level E2 from E1?
- Suppose the external source has a power of 100 W. What would be the rate of photon emission?
