Tag: physics

Questions Related to physics

If $v _{g}, v _{x}$, and $v _{m}$ are speeds of gamma rays, $X$ rays, and microwaves respectively in vacuum, then:

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

  1. $V _{g} < V _{x} < V _{m}$

  2. $V _{g}>V _{x}>V _{m}$

  3. $V _{g} < V _{x}> V _{m}$

  4. $V _{g}=V _{x}=V _{m}$

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Correct Option: D
Explanation:
The gamma rays, $X-$ rays and the microwaves are the Electromagnetic waves and the speed of all the electromagnetic waves remains the same in vacuum irrespective of other parameters. All will travel at the speed of light.

$V _{g}=V _{x}=V _{m}$ 

 The speed of Electromagnetic waves is always the same in vacuum. So, option $(D)$ is correct.

Which of the following electromagnetic waves is used in medicine to destroy cancer cell?

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

  1. IR- rays

  2. Visible rays

  3. Gamma rays

  4. Ultraviolet rays

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Correct Option: C
Explanation:
Gamma rays are dominantly used in medicines to destroy the cells that are cancer affected. The gamma rays are chosen such that its energy does not harm the healthy cells.

Therefore, the rays used in medicine to destroy cancer cells are Gamma rays.

A. wavelength of microwave is greater than that of ultraviolet rays.
B. The wave length of infrared rays is lesser than that of ultraviolet rays.
C. wavelength of microwave is lesser than that of ultraviolet rays
D. Gamma rays has shortest wavelength in the electromagnetic spectrum.
Choose the correct option from the given options.

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

  1. A and B are true

  2. B and C are true

  3. C and D are true

  4. A and D are true

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Correct Option: D
Explanation:
The wavelength and the frequency of the Electromagnetic waves are inversely proportional to each other.

$A$. The wavelength of Microwave is greater than UV rays.
The frequency of the microwave is less than that of the Ultraviolet rays, the wavelength of the Microwaves will be longer than the Ultraviolter rays.

$D$. Gamma rays have the shortest wavelength in the EM spectrum.
The frequency of the gamma rays is the highest in the electromagnetic spectrum. So, it will have the shortest wavelength.

The wavelength of the infrared is higher than the Ultraviolet rays and also the wavelength of the microwave is higher than Ultraviolet rays. So, options $B$ and $C$ are not true.
Option $(D)$ is correct.

Which of the following is absorbed by the ozone layer ?

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

  1. only gamma rays

  2. visible light

  3. radio waves

  4. ultraviolet

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Correct Option: D
Explanation:

Ozone is a molecule made of three oxygen atom or $O _3$. When ultraviolet light in the range $240nm$ and $320 nm$ strikes an ozone molecule, it absorbs the energy and the $O _3$ changes to $O _2$ and $O$. The $O$ atom soon combines with another $O _2$ molecule to form $O _3$ and is ready to absorb ultra violet light.

Which wavelength of sun is used finally as electric energy? 

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

  1. Radio waves

  2. Infrared waves

  3. Visible light

  4. Micro waves

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Correct Option: B
Explanation:

The heating property of Infra red waves is used in solar heater and solar cells, Hence option (b) is correct. 

What is the type of invisible radiation from space that can be detected from Earth's surface?

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

  1. Gamma rays

  2. X-rays

  3. Infrared radiation

  4. Radio waves

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Correct Option: A

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.