Tag: electromagnetic spectrum

Questions Related to electromagnetic spectrum

Which of the following colors of light has the lowest frequency?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Yellow

  2. Violet

  3. Orange

  4. Blue

  5. Green

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Correct Option: C
Explanation:

The color with the lowest frequency corresponds to the longest wavelength, which is orange in this case.

Identify the waves with the largest wavelengths .

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Radio

  2. Gamma Rays

  3. X-Rays

  4. Visible Light

  5. Infrared Radiation

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Correct Option: A
Explanation:

Order of wavelength from smallest to largest :

Gamma rays < X-rays < Visible light < Infrared Radiation < Microwaves < Radio waves
Thus radio waves has the largest wavelength.

Find out the wavelength of violet light which has a frequency of $7.5 \times 10^{14}Hz$ ?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. $2.25\times 10^{23}m$

  2. $2.5\times 10^{5}m$

  3. $4\times 10^{-7}m$

  4. $7.5\times 10^{-7}m$

  5. $2.25\times 10^{7}m$

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Correct Option: C
Explanation:

Given :    $\nu = 7.5 \times 10^{14}$  Hz

Speed of violet light (EM wave)     $v = 3 \times 10^8$ m/s
Thus wavelength of violet light         $\lambda = \dfrac{v}{\nu}  = \dfrac{3 \times 10^8}{7.5 \times 10^{14}}  =4 \times 10^{-7}$ m

In an electromagnetic spectrum, identify which of the following lists are ordered from longest wavelength to shortest wavelength?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. X ray, ultraviolet, visible light

  2. visible light, ultraviolet , X-ray

  3. ultraviolet, X-ray, visible light

  4. ultraviolet, visible light, X-ray

  5. X-ray, visible light, ultraviolet

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Correct Option: B
Explanation:

Decreasing order of wavelength :

 Visible light > ultraviolet > X-ray
Thus option B is correct.

Which of the following has the shortest wavelength? 

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Red light

  2. Blue light

  3. Gamma rays

  4. X rays

  5. Radio waves

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Correct Option: C
Explanation:

Increasing order of wavelength :

Gamma rays < X-rays < Blue light < Red light < Radio waves
Thus gamma ray has the shortest wavelength.

The sun delivers $10^3\, Wm^{-2}$ of electromagnetic flux on the earth's surface. The total power that is incident on a roof of dimensions $6 \,m \times 30\, m$ is 

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. $1.8 \times 10^5\, W$

  2. $7.2 \times 10^5\, W$

  3. $0.9 \times 10^5\, W$

  4. $4.5 \times 10^5\, W$

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Correct Option: A
Explanation:

Given, electromagnetic flux $=10^3\, Wm^{-2}$
The area of roof $A= 6\, m \times 30\, m$
$=180 \, m^2$
The total power incident on roof
$P=10^3 \times 180$
$=1.8\times 10^5 \, W$

Clear images of soft tissues can be well studied using.

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. MRI

  2. X-rays

  3. Ultrasonics

  4. I.R rays

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Correct Option: A
Explanation:

MRI gives very detailed pictures of soft tissues like the brain

The method of using radio waves to cure some diseases are called

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Physiotherapy

  2. Netratherapy

  3. Radiotherapy

  4. Radiometry

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Correct Option: C

A group of wavelengths is called

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Wave

  2. Echo

  3. Sound Wave

  4. Spectrum

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Correct Option: D

Wave length of visible spectrum extends from

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. 0.4 $\mu$ m- 0.7 $\mu$m

  2. 0.5 nm - 6 nm

  3. 5 $\mu$ m - 60 $\mu$m

  4. 50 nm - 60 nm

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Correct Option: A