Out of the following options which one can be used to produce a propagating electromagnetic wave?

1. a stationary charge.
2. a chargeless particle.
3. an accelerating charge.
4. a charge moving at constant velocity.

Subtopic:  Generation of EM Waves |
 89%
From NCERT
NEET - 2016
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The energy of the EM waves is of the order of \(15~\mathrm{keV}\). To which part of the spectrum does it belong?
1. X-rays
2. Infrared rays
3. Ultraviolet rays
4. \(\gamma\)-rays

Subtopic:  Electromagnetic Spectrum |
 58%
From NCERT
NEET - 2015
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The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma rays is:
1. gamma rays, ultraviolet, infrared, microwaves.
2. microwaves, gamma rays, infrared, ultraviolet.
3. infrared, microwave, ultraviolet, gamma rays.
4. microwave, infrared, ultraviolet, gamma rays.
Subtopic:  Electromagnetic Spectrum |
 84%
From NCERT
AIPMT - 2011
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Which colour of the light has the longest wavelength?

1. violet 2. red
3. blue 4. green
Subtopic:  Electromagnetic Spectrum |
 87%
From NCERT
NEET - 2019
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The EM wave with the shortest wavelength among the following is:
1. Ultraviolet rays  2. \(X\)-rays
3. Gamma-rays  4. Microwaves  
Subtopic:  Electromagnetic Spectrum |
 77%
From NCERT
NEET - 2020
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The frequency order for \(\gamma\text-\)rays (\(b\)), \(X\text-\)rays (\(a\)), and \(UV\text-\)rays (\(c\)) is:
1. \( b>a>c \) 2. \( a>b>c \)
3. \( c>b>a \) 4. \( a>c>b\)
Subtopic:  Electromagnetic Spectrum |
 81%
From NCERT
AIPMT - 2000
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The biological importance of the ozone layer is:

1. it stops ultraviolet rays.
2. ozone layer reduces the greenhouse effect.
3. ozone layer reflects radio waves.
4. ozone layer controls \(\mathrm{O}_2 / \mathrm{H}_2\) ratio in the atmosphere.


 

Subtopic:  Electromagnetic Spectrum |
 85%
From NCERT
AIPMT - 2001
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The magnetic field in a plane electromagnetic wave is given by \({B}=\left(2 \times 10^{-7}\right)\sin \left(0.5 \times 10^3 {x}+1.5 \times 10^{11} {t}\right )~\text{T}\). The wavelength and frequency of the wave are respectively:
1. \( 2.16~\text{cm}, 24.1~\text{GHz} \) 2. \( 0.29~\text{cm}, 13.7~\text{GHz} \)
3. \( 3.23 ~\text{cm}, 20.0~\text{GHz} \) 4. \( 1.26~\text{cm}, 23.9~\text{GHz}\)
Subtopic:  Properties of EM Waves |
 72%
From NCERT
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The magnetic field in a plane electromagnetic wave is given by;
\(B_y=\left(2 \times 10^{-7}\right) \sin \left(0.5 \times 10^3 {x}+1.5 \times 10^{11} {t}\right)~\text{T}\).
The expression for the electric field is:
1. \(E_z=60 \sin \left(0.5 \times 10^3 x+1.5 \times 10^{11} t\right) ~\text{V/m} \)
2. \(E_z=60 \sin \left(1.5 \times 10^3 x+0.5 \times 10^{11} t\right) ~\text{V/m} \)
3. \(E_z=55 \sin \left(0.5 \times 10^3 x+1.5 \times 10^{11} t\right) ~\text{V/m} \)
4. \(E_z=55 \sin \left(1.5 \times 10^3 x+0.5 \times 10^{11} t\right) ~\text{V/m} \)
Subtopic:  Properties of EM Waves |
 82%
From NCERT
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Assume a bulb of efficiency \(2.5\%\) as a point source. The peak values of the electric field and magnetic field produced by the radiation coming from a \(100~\text{W}\) bulb at a distance of \(3~\text{m}\) are respectively:

1. \( 2.5 ~\text{V/m}, ~2.2 \times 10^{-8} ~\text{T} \)
2. \( 3.6 ~\text{V/m}, ~ 3.6 ~\text{T} \)
3. \( 4.07~\text{V/m},~ 1.4 \times 10^{-8} ~\text{T}\)
4. \( 4.2 ~\text{V/m}, ~3.4 \times 10^{-6}~\text{T}\)
Subtopic:  Properties of EM Waves |
 53%
From NCERT
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