Tag: electromagnetic waves

Questions Related to electromagnetic waves

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

Show answer
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

Show answer
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. ${10}^{-7}:cm$

Show answer
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.

Which of the following lights has maximum wavelength?

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

  1. $\gamma$ - rays

  2. X - rays

  3. UV - rays

  4. Visible rays

Show answer
Correct Option: D
Explanation:

wavelength of following lights are:
$\gamma$-rays:$10pm$
x-rays:($10pm-10nm$)
UV-rays:($10nm-380nm$)
visible rays:($380nm-750nm$)
so,visible rays has maximum wavelength.

Les-energetic electromagnetic radiations like X-rays are generated in the

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

  1. Radiation zone

  2. Convection zone

  3. Photosphere

  4. Chromosphere

Show answer
Correct Option: A
Explanation:

We know that radiation is emission or transmission of energy in the form of waves or particles.

$X$ rays make up $X$-radiation, a form of electromagnetic radiation.
That's why $X$ rays are generated in radiation zone.

Infrared radiations are used in

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

  1. Microwave ovens

  2. Long distance photography

  3. Microscopes

  4. Treatment of cancer

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Correct Option: A
Explanation:

Infrared radiation are used in microwaves ovens in electronagnetiic spectrum frequency and energy of microwave is smaller than visible light water contain is required for coobing food in microwave oven almost all food item contain some water contain.Microwaves interact with water molecules all atoms via their electric and magnetic fileds. Temprature of water molecules increases by this these water molecule share this energy with neighbouring food molecules, heating up the food.

Hydrogen atom does not emit X-rays because

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

  1. it contains only a single electron

  2. energy levels in it are far apart

  3. its size is very small

  4. energy levels in it are very close to each other

Show answer
Correct Option: D
Explanation:

Hydrogen is the least energetic element. Even the most energetic line that hydrogen emits (when an electron drops down from the second shell to the first) has only enough energy to be an ultraviolet photon. This is because the energy levels in hydrogen atom are very close. So hydrogen atoms do not emit X rays.

The part of the electromagnetic spectrum which is produced by bombarding a metal target with high energy electrons is :

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

  1. Ultraviolet 

  2. X-Rays

  3. Infrared 

  4. Gamma Rays

Show answer
Correct Option: B
Explanation:

X-rays are produced by bombarding a metal target with high energy electrons.

Which one of following have highest frequency?

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

  1. radio waves.

  2. infrared.

  3. ultraviolet.

  4. gamma rays.

Show answer
Correct Option: D
Explanation:

Frequency of Radio waves = $<3\times { 10 }^{ 9 }$Hz

Frequency of infrared waves = $3\times { 10 }^{ 9 }-3\times { 10 }^{ 11 }$Hz
Frequency of ultraviolet waves = $7.5\times { 10 }^{ 14 }-3\times { 10 }^{ 17 }$Hz
Frequency of gamma rays = $>3\times { 10 }^{ 20 }$Hz

So Gamma rays have highest frequency.