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Answer briefly. What are radio waves? - Physics

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प्रश्न

Answer briefly.

What are radio waves?

टीपा लिहा

उत्तर

  1. Radio waves are produced by accelerated motion of charges in a conducting wire. The frequency of waves produced by the circuit depends upon the magnitudes of the inductance and the capacitance.
  2. Thus, by choosing suitable values of the inductance and the capacitance, radio waves of the desired frequency can be produced.
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पाठ 13: Electromagnetic Waves and Communication System - Exercises [पृष्ठ २४१]

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बालभारती Physics [English] 11 Standard Maharashtra State Board
पाठ 13 Electromagnetic Waves and Communication System
Exercises | Q 2. (ix) | पृष्ठ २४१

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What role dose infra-red radiation play in maintain the Earth’s warmth


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Use the formula λm T= 0.29 cm K to obtain the characteristic temperature ranges for different parts of the electromagnetic spectrum. What do the numbers that you obtain tell you?


State an additional use of the X-rays waves


A wave has wavelength 50 Å.

  1. Name the wave.
  2. State its speed in vacuum.
  3. State its one use.

State Moseley's law


(a) Give a list of at least five radiations, in order of their increasing frequencies, which make up the complete electromagnetic spectrum.

(b) Which of the radiation mentioned by you in part (a) has the highest penetrating power.


Name two electromagnetic waves of frequency smaller than that of violet light. State one use of each.


Name the rays or waves  of highest frequency .


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Name three properties of ultraviolet radiations which are similar to visible light.


An electromagnetic wave has a frequency of 500 MHz and a wavelength of 60 cm Calculate the velocity of the wave.


The X-ray beam emerging from an X-ray tube


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X-ray incident on a material
(a) exerts a force on it
(b) transfers energy to it
(c) transfers momentum to it
(d) transfers impulse to it.


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

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.


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.)


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.


Name two sources of infrared radiation.


Choose the correct option.

How does the frequency of a beam of ultraviolet light change when it travels from air into glass?


Answer briefly.

Give two uses of ultraviolet rays.


The fundamental frequency of an open organ pipe is 300 Hz. The first overtone of this pipe has same frequency as first overtone of a closed organ pipe. If speed of sound is 330 m/s, then the length of closed organ pipe is:


The frequency of x-rays, y-rays and ultraviolet rays are respectively a, b and c. Then:-


What is the speed of radio waves in vacuum?


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