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प्रश्न
Answer briefly.
Give two uses of radio waves.
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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?
If the earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain.
To which part of electromagnetic spectrum does a wave of frequency 3 × 1013 Hz belong?
To which part of the electromagnetic spectrum does a wave of frequency 5 × 1019 Hz belong?
What physical quantity is the same for X-rays of wavelength 10−10 m, red light of wavelength 6800 Å and radiowaves of wavelength 500 m?
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)X-rays,
Name the region beyond the red end of the spectrum.
State the approximate range of wavelength associated with visible light.
Name the rays or waves of highest frequency .
Name two sources, each of infrared radiations and ultraviolet radiations.
Characteristic X-rays may be used to identify the element from which they are being emitted. Can continuous X-rays be used for this purpose?
Consider a photon of a continuous X-ray coming from a Coolidge tube. Its energy comes from
The X-ray coming from a Coolidge tube has a cutoff wavelength of 80 pm. Find the kinetic energy of the electrons hitting the target.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
Find the maximum potential difference which may be applied across an X-ray tube with tungsten target without emitting any characteristic K or L X-ray. The energy levels of the tungsten atom with an electron knocked out are as follows.
| Cell containing vacancy | K | L | M |
| Energy in keV | 69.5 | 11.3 | 2.3 |
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 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.)
The short-wavelength limit shifts by 26 pm when the operating voltage in an X-ray tube is increased to 1.5 times the original value. What was the original value of the operating voltage?
(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 three radiations and their wavelength range which are invisible and beyond the violet end of the visible spectrum.
Identify the part of the electromagnetic spectrum used in
(i) radar and
(ii) eye surgery. Write their frequency range.
Name any two electromagnetic waves which have a frequency higher than that of violet light. State one use of each.
Answer briefly.
Can we produce a pure electric or magnetic wave in space? Why?
Answer briefly.
Why light waves travel in a vacuum whereas sound waves cannot?
Answer briefly.
Name the most harmful radiation entering the Earth's atmosphere from outer space.
Answer briefly.
What is a carrier wave?
Calculate the wavelength of a microwave of a frequency of 8.0 GHz.
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 radio can tune to any station in the 7.5 mHz to 12 MHz band. What is corresponding wave length band.
Radio waves of constant amplitude can be generated with.
One requires 11eV of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in ______.
The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is ______.
Write two uses of the following radiation.
X-rays
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.
Photons of an electromagnetic radiation has an energy 11 keV each. To which region of electromagnetic spectrum does it belong?
Give any two uses of infrared waves.
Name two electromagnetic waves of wavelength smaller than that of violet light.
