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प्रश्न
Answer briefly.
Give two uses of radio waves.
उत्तर
- Radio waves are used for wireless communication purposes.
- They are used for radio broadcasting and transmission of TV signals.
- Cellular phones use radio waves to transmit voice communication in the ultra-high frequency (UHF) band.
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संबंधित प्रश्न
How are infrared waves produced?
Identify the part of the electromagnetic spectrum which is:
produced by bombarding a metal target by high speed electrons.
Give a reason for the following:
It is necessary to use satellites for long-distance TV transmission. Why?
What is the range of the wavelength of the following electromagnetic waves?
(A) Radio waves.
State the approximate range of wavelength associated with visible light.
State the approximate range of wavelength associated with infrared rays.
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.
An electromagnetic wave has a frequency of 500 MHz and a wavelength of 60 cm Calculate the velocity of the wave.
How are X-rays produced?
In a Coolidge tube, electrons strike the target and stop inside it. Does the target get more and more negatively charged as time passes?
X-ray and visible light travel at the same speed in vacuum. Do they travel at the same speed in glass?
Is it possible that in a Coolidge tube characteristic Lα X-rays are emitted but not Kα X-rays?
Can Lα X-ray of one material have shorter wavelength than Kα X-ray of another?
If the current in the circuit for heating the filament is increased, the cutoff wavelength
One of the following wavelengths is absent and the rest are present in the X-rays coming from a Coolidge tube. Which one is the absent wavelength?
50% of the X-ray coming from a Coolidge tube is able to pass through a 0.1 mm thick aluminium foil. The potential difference between the target and the filament is increased. The thickness of the aluminium foil that will allow 50% of the X-ray to pass through 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.
Consider a photon of continuous X-ray and a photon of characteristic X-ray of the same wavelength. Which of the following is/are different for the two photons?
Find the energy, the frequency and the momentum of an X-ray photon of wavelength 0.10 nm.
(Use Planck constant h = 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
Heat at the rate of 200 W is produced in an X-ray tube operating at 20 kV. Find the current in the circuit. Assume that only a small fraction of the kinetic energy of electrons is converted into X-rays.
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.)
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
X-rays
Arrange the following electromagnetic waves in increasing order of their frequencies (i.e. begin with the lowest frequency):
Visible light, y rays, X rays, microwaves, radio waves, infrared radiations, and ultraviolet radiation.
Name the radiation of the electromagnetic spectrum which is used for the following:
To photograph internal parts of the human body and Give the frequency range
How will you investigate the existence of the radiation beyond the red and violet extremes of the spectrum?
State three properties of ultra-violet radiation similar to visible light.
What is the wavelength of the wave whose frequency is 1012 Hz? Name the electromagnetic wave.
Answer briefly.
Why high-frequency carrier waves are used for the transmission of audio signals?
Calculate the wavelength of a microwave of a frequency of 8.0 GHz.
An e.m. wave exerts pressure on the surface on which it is incident. Justify.
For television broadcasting, the frequency employed is normally
Ozone layer above the earth's atmosphere will
SONAR emits which of the following waves?
All components of the electromagnetic spectrum in a vacuum have the same ______
The magnetic field of a beam emerging from a filter facing a floodlight is given by B0 = 12 × 10–8 sin (1.20 × 107z – 3.60 × 1015t) T. What is the average intensity of the beam?
Given below in the left column are different modes of communication using the kinds of waves given in the right column.
| A. | Optical Fibre Communication |
P. | Ultrasound |
| B. | Radar | Q. | Infrared Light |
| C. | Sonar | R. | Microwaves |
| D. | Mobile Phones | S. | Radio Waves |
From the options given below, find the most appropriate match between entries in the left and the right column.
