Q. No.A laser emits monochromatic light with a frequency of \(6.0\times 10^{14}~\text{Hz}.\) The energy of a single photon in this light beam is:
\((\text{take}~h=6.63\times10^{-34}~\text{J-s})\)
\((\text{take}~h=6.63\times10^{-34}~\text{J-s})\)
| 1. | \(3.98\times 10^{-16}~\text{J}\) | 2. | \(3.98\times 10^{-17}~\text{J}\) |
| 3. | \(3.98\times 10^{-18}~\text{J}\) | 4. | \(3.98\times 10^{-19}~\text{J}\) |
Subtopic: Particle Nature of Light |
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\(6\times10^5~\text{J} \) of electromagnetic energy is incident on a surface in time \(t_0.\) Then the total momentum imparted if the surface is completely absorbing is:
1. \(2 \times 10^{-3}~\text{kg-m/s}\)
2. \(10^{-3} ~\text{kg-m/s}\)
3. \(10^{-2}~\text{kg-m/s}\)
4. \(2 \times 10^{-4}~\text{kg-m/s}\)
1. \(2 \times 10^{-3}~\text{kg-m/s}\)
2. \(10^{-3} ~\text{kg-m/s}\)
3. \(10^{-2}~\text{kg-m/s}\)
4. \(2 \times 10^{-4}~\text{kg-m/s}\)
Subtopic: Particle Nature of Light |
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Match the following items in Column-I with their corresponding descriptions in Column-II:
Codes:
| Column-I | Column-II | ||
| \(\mathrm{(A)}\) | Radiation pressure | \(\mathrm{(I)}\) | Particle nature of radiation |
| \(\mathrm{(B)}\) | Threshold wavelength | \(\mathrm{(II)}\) | Stopping potential |
| \(\mathrm{(C)}\) | Maximum kinetic energy of photoelectron | \(\mathrm{(III)}\) | Maximum wavelength of an incident photon in photoelectric effect |
| \(\mathrm{(D)}\) | Quantisation of angular momentum of the electron | \(\mathrm{(IV)}\) | De-Broglie hypothesis |
| 1. | \(\mathrm{A\text-I,B\text-III,C\text- II,D\text-IV}\) |
| 2. | \(\mathrm{A\text-III,B\text-I,C\text- II,D\text-IV}\) |
| 3. | \(\mathrm{A\text-I,B\text- III,C\text-IV,D\text- II}\) |
| 4. | \(\mathrm{A\text-IV,B\text-II,C\text-I,D\text-III}\) |
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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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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The energy flux of sunlight reaching the Earth's surface is \(2.776 \times 10^3~\text{W/m}^2.\) The photons in sunlight have an average wavelength of \(650~\text{nm}. \) How many photons per square metre are incident on the Earth per second?
| 1. | \(9 \times 10^{31}\) | 2. | \(9 \times 10^{25}\) |
| 3. | \(9 \times 10^{21}\) | 4. | \(9 \times 10^{24}\) |
Subtopic: Particle Nature of Light |
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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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If the minimum wavelength emitted by an \(X\text-\)ray tube is \(0.041~\text{nm},\) the corresponding anode voltage applied to the \(X\text-\)ray tube is:
(Planck’s constant, \(h=6.63 \times 10^{-34}~\text{J-s}\))
1. \(15~\text{kV}\)
2. \(30~\text{kV}\)
3. \(45~\text{kV}\)
4. \(60~\text{kV}\)
(Planck’s constant, \(h=6.63 \times 10^{-34}~\text{J-s}\))
1. \(15~\text{kV}\)
2. \(30~\text{kV}\)
3. \(45~\text{kV}\)
4. \(60~\text{kV}\)
Subtopic: Particle Nature of Light |
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Which of the following statements about photons is incorrect?
| 1. | The rest mass of a photon is zero. |
| 2. | The momentum of a photon is given by \(h\nu/c. \) |
| 3. | The energy of a photon is \(h\nu.\) |
| 4. | Photons do not exert any pressure. |
Subtopic: Particle Nature of Light |
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How much energy is carried by each photon emitted from a \(5~\text{mW}\) laser operating at a wavelength of \(663~\text{nm}\)?
(take \(h=6.63 \times10^{-34}\) J-s and \(c=3 \times 10^8\) m/s)
1. \( 3 \times 10^{-18} ~\text{J} \)
2. \( 3 \times 10^{-19}~ \text{J} \)
3. \( 3 \times 10^{-20} ~\text{J} \)
4. \( 3 \times 10^{-21} ~\text{J}\)
(take \(h=6.63 \times10^{-34}\) J-s and \(c=3 \times 10^8\) m/s)
1. \( 3 \times 10^{-18} ~\text{J} \)
2. \( 3 \times 10^{-19}~ \text{J} \)
3. \( 3 \times 10^{-20} ~\text{J} \)
4. \( 3 \times 10^{-21} ~\text{J}\)
Subtopic: Particle Nature of Light |
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