Tag: electromagnetic waves

Questions Related to electromagnetic waves

A potential difference of 0.1kV is applied across an X-ray tube. The ratio of the de-Broglie wave lengths of incident electron, striking the target to the shortest wavelength of X-rays produced nearly (e/m of electron= $1.8\times 10^{11}C/kg$) ?

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. 1:1

  2. 1:10

  3. 1:100

  4. 1:1000

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Correct Option: D

Minimum energy that a $\gamma-ray$ must have to give rise to an electron-position pair is

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. $0.51\ MeV$

  2. $1.02\ MeV$

  3. $2.04\ MeV$

  4. $1.53\ MeV$

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Correct Option: A

Radio waves of constant amplitude can be generated with 

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. filter

  2. rectifier

  3. FET

  4. oscillator

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Correct Option: D
Explanation:

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum. The electromagnetic waves can be produced using oscillator.

Infrared radiation was discovered in 1860  by

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. William Wallaston

  2. William Herschel

  3. William Roentgen

  4. Thomas Young

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Correct Option: B
Explanation:

Herschel was testing filters for the sun so he could observe sun spots. When using a red filter he found there was a lot of heat produced. Herschel discovered infrared radiation in sunlight by passing it through a prism and holding a thermometer just beyond the red end of the visible spectrum.This thermometer was meant to be a control to measure the ambient air temperature in the room. He was shocked when it showed a higher temperature than the visible spectrum. Further experimentation led to Herschel's conclusion that there must be an invisible form of light beyond the visible spectrum.

Which one of the following is unstable

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. $\alpha$ ray

  2. $y-ray$

  3. proton

  4. neutron

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Correct Option: A
Explanation:

$\alpha -ray$ is the sub atomic particles and their associated energy that are released during the decomposition of the unstable nuclei are referred to as radiation-

so that the correct option is A.

The waves relevant to telecommunications are

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. visible light

  2. infrared

  3. ultraviolet

  4. microwave

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Correct Option: D
Explanation:

visible light, infrared and ultraviolet radiation cannot be used for communication.

Which wavelength of harmful UV-radiations is prevented by ozone layer in entering the Earth atmosphere?

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. $210-300nm$

  2. $200-310nm$

  3. $120-210nm$

  4. $400-700nm$

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Correct Option: C

The waves related to tele-communication are

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. infrared

  2. visible light

  3. microwaves

  4. ultraviolet rays

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Correct Option: C
Explanation:

Infrared waves are generally used to transmit information from remote controls.

Visible light is generally used for photography

Microwaves are used to transmit satellite television and for mobile phones.

A wave has a wavelength of $0.01A^o$. Name the wave:

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. X rays

  2. Micro waves

  3. Gamma waves

  4. Radio waves

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Correct Option: C
Explanation:

Electromagnetic radiation is classified into types according to the frequency of the wave. These types include, in order of increasing frequency, radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
The frequency is the inverse of wavelength. Hence, in the order of increasing wavelength, the waves are Gamma rays ($<1nm$), X-rays ($1-{ 10 }nm$), infra red rays ($700-{ 10 }^{ 5 }nm$), micro waves (${ 10 }^{ 5 }-{ 10 }^{ 8 }nm$), radio waves (${ >10 }^{ 8 }nm$).
Therefore, gamma rays has a wavelength of $0.01 \mathring{A}$.

Name the high energetic invisible electromagnetic wave which helps in the study of structure of crystals.

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. $X$-rays

  2. Cathod rays

  3. Gamma rays

  4. All of the above

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Correct Option: A
Explanation:

The electromagnetic wave which helps in the study of structure of crystals is X-rays.
If a beam of x rays is passed through a crystal, it makes a pattern on a photographic plate. The pattern is called crystallogram (the arrangement of the atoms each crystal has its own crystallogram). It reveals the crystal`s internal structure.