Tag: physics

Questions Related to physics

If the source of power $4kwW$ produces $10^20$ photons/second, the radiation belongs to the part of a spectrum called

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

  1. X rays

  2. Ultraviolet rays

  3. Microwaves

  4. Gamma rays

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Correct Option: A

A wave has wavelength $50A^o$. Which of the following is a use of this wave?

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

  1. in detection of fracture in bones.

  2. in detection of planets

  3. in detection of water

  4. in detection of air

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Correct Option: A
Explanation:

X-rays has a wavelength of $50 \mathring{A}$.
X-rays are used by doctors to see inside people. The machines are managed by a trained x-ray technician. They pass easily through soft tissues, but not so easily through bones.
Hence, they help in detecting fractures in bones.

Name the radiations of wavelength just shorter than $4\times 10^{-7}m$.

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

  1. Infraviolet

  2. Ultraviolet

  3. Infrared

  4. Ultrared

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Correct Option: B
Explanation:

The range of wavelength for visible light lies between, ${ 400 \ nm }<\lambda <{ 700 \ nm }$.

$\lambda $ just less than 400 nm is Ultraviolet.
$\lambda $ just greater than 700 nm is Infrared.

Name the radiation which can be detected by a thermophile.

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

  1. infrared radiation

  2. ultraviolet radiation

  3. X-rays

  4. All of the above

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Correct Option: A

Name the rays or waves used for taking photographs in dark.

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

  1. Infrared rays

  2. Ultraviolet rays

  3. X-rays

  4. Gamma rays

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Correct Option: A
Explanation:

Photographers use film that is sensitive to infrared rays to take pictures in places where there is no visible light. 
IR light is longer in wavelength than visible light and focuses differently. Regular photographic lenses are made for visible light photography without any regard to what happens when photographing out of band light like IR. Therefore each lens design and focal length, even each focal length within a zoom lens will focus IR light differently.
Hence, infrared light is used for taking pictures in the dark.

Name the rays or waves produced by the changes in the nucleus of an atom.

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

  1. X-rays

  2. UV rays

  3. Gamma rays

  4. IR rays

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Correct Option: C
Explanation:

Gamma rays are classically produced by the decay of atomic nuclei as they transition from a high energy state to a lower state known as gamma decay, but may also be produced by other processes. Paul Villard, a French chemist and physicist, discovered gamma radiation in $1900$, while studying radiation emitted from radium. Villard's radiation was named "gamma rays" by Ernest Rutherford in $1903$.
Hence,  the rays or waves produced by the changes in the nucleus of an atom is Gamma rays.

A wave has wavelength $50A^o$. State the speed of wave in vacuum.

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

  1. $3\times 10^8ms^{-1}$

  2. >$3\times 10^8ms^{-1}$

  3. <$3\times 10^8ms^{-1}$

  4. Insufficient information

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Correct Option: A
Explanation:

X-rays has a wavelength of $50\ A^o$.
All electromagnetic radiation, of which radio waves and X-rays are examples, travels at the velocity of light, in a vacuum. The only difference between the two is that the frequency of X-rays is very much higher than radio waves.
Hence, X-rays travels at a speed of ${ 3\times 10 }^{ 8 }m/s$.

Read the following statements.
a. Ozone in found mostly in the stratosphere.
b. Ozone layer lies 55-75 kms above the surface of the earth.
c. Ozone absorbs ultraviolet radiation from the Sun.
d. Ozone layer has no significance for life on the earth.
Which set of the statements is correct ?

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

  1. a and c

  2. b and d

  3. b and c

  4. a and d

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Correct Option: A
Explanation:

Ozone layer also called ozonosphere contains relatively high concentrations of ozone ($O _{3}$) molecules. Approximately 90% of atmospheric ozone occurs in stratosphere, the region extending from 10 - 18 km to 50 km above the earth's surface. The ozone layer effectively blocks certain types of ultraviolet and other forms of radiations that could injure or kill most living things.

Which of the following is the infrared wavelength?

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

  1. ${10}^{-4}:cm$

  2. ${10}^{-5}:cm$

  3. ${10}^{-6}:cm$

  4. ${10}^{-7}:cm$

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Correct Option: A
Explanation:

The wavelength of infrared region is $8\times{10}^{-5}:cm$ to  $3\times{10}^{-3}:cm$. So maximum wavelength of infrared region $=8\times{10}^{-5}:cm\approx{10}^{-4}:cm$.

Consider the following processes
(i) Electrical oscillation
(ii) Rapid deceleration of fast electrons
(iii) Atomic transition
Which of these are likely to produce visible light?

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

  1. (iii) only

  2. (ii) and (iii)

  3. (i) and (iii)

  4. (i), (ii) and (iii)

Show answer
Correct Option: D
Explanation:

Visible light means i.e visible to human eye.

It runs about $700-400㎚$
So Basically all of these options
  1. Electrical oscillation
  2. Rapid deceleration of fast electrons
  3. Atomic transition
This is basically theoretical question.