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Q. No.A laser with a power output of \(2~\text{mW}\) operates at a wavelength of \(500~\text{nm}.\) The number of photons emitted per second is:
(Planck's constant, \(h=6.6\times 10^{-34}~\text{J-s}\) & speed of light, \(c=3.0\times 10^8~\text{m/s}\) )
1. \( 5 \times 10^{15} \)
2. \(1.5 \times 10^{16} \)
3. \(1 \times 10^{16} \)
4. \(2 \times 10^{16}\)
Subtopic: Particle Nature of Light |
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Two light sources emit \(\mathrm{X}\)-rays with a wavelength of \(1~\text{nm}\) and visible light with a wavelength of \(500~\text{nm},\) respectively. Both sources emit light with the same power of \(200~\text W.\) What is the ratio of the number density of photons of \(\mathrm{X}\)-rays to the number density of photons of visible light for the given wavelengths?
| 1. | \( \dfrac{1}{500} \) | 2. | \( 500 \) |
| 3. | \( \dfrac{1}{250} \) | 4. | \( 250\) |
Subtopic: Particle Nature of Light |
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JEE
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Given below are two statements :
| Assertion (A): | Two photons having equal linear momenta have equal wavelengths. |
| Reason (R): | If the wavelength of the photon is decreased, then the momentum and energy of a photon will also decrease. |
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | (A) is false but (R) is true. |
Subtopic: Particle Nature of Light |
From NCERT
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If a substance absorbs \(500~\text{nm}\) wavelength radiation and emits radiation of wavelength \(600~\text{nm},\) then the net change in energy is: (take \(hc=1240~\text{eV-nm}\))
1. \(1.2\times10^{-3}~\text{eV}\)
2. \(3.0\times10^{-4}~\text{eV}\)
3. \(4.1\times10^{-1}~\text{eV}\)
4. \(5.2\times10^{-4}~\text{eV}\)
1. \(1.2\times10^{-3}~\text{eV}\)
2. \(3.0\times10^{-4}~\text{eV}\)
3. \(4.1\times10^{-1}~\text{eV}\)
4. \(5.2\times10^{-4}~\text{eV}\)
Subtopic: Particle Nature of Light |
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Average force exerted on a non-reflecting surface at normal incidence is \(2.4 \times 10^{-4} \mathrm{~N}.\) If \(360 \mathrm{~W} / \mathrm{cm}^2\) is the light energy flux during span of \(1\) hour \(30\) minutes, Then the area of the surface is:
1. \(0.02 \mathrm{~m}^2\)
2. \(0.2 \mathrm{~m}^2\)
3. \(20 \mathrm{~m}^2\)
4. \(0.1 \mathrm{~m}^2\)
1. \(0.02 \mathrm{~m}^2\)
2. \(0.2 \mathrm{~m}^2\)
3. \(20 \mathrm{~m}^2\)
4. \(0.1 \mathrm{~m}^2\)
Subtopic: Particle Nature of Light |
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