A monochromatic source of light emits \(50~\text{W}\) at a wavelength of \(400~\text{nm}.\) The number of photons emitted per second is approximately (take \({hc} = 1240~\text{eV-nm}\)):
1. \(10^{20}\) 
2. \(10^{25}\)
3. \(10^{30}\)
4. \(10^{40}\)
Subtopic:  Particle Nature of Light |
 80%
Level 1: 80%+
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The work function of cesium is \(2.14 ~\text{eV}.\) The threshold frequency for cesium is:
1. \(5.03\times10^{12}~\text{Hz}\) 2. \(6.12\times10^{14}~\text{Hz}\)
3. \(5.16\times10^{14}~\text{Hz}\) 4. \(6.51\times10^{12}~\text{Hz}\)
Subtopic:  Particle Nature of Light |
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Level 2: 60%+
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Which of the following demonstrates the particle nature of light?
1. photoelectric effect 2. interference
3. refraction 4. polarisation
Subtopic:  Particle Nature of Light |
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Level 1: 80%+
AIPMT - 2001
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Two photons have:

1. equal wavelengths have equal linear momenta.
2. equal energies have equal linear momenta.
3. equal frequencies have equal linear momenta.
4. equal linear momenta have equal wavelengths.

Subtopic:  Particle Nature of Light |
Level 3: 35%-60%
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Let \(n_r\) and \(n_b\) be respectively the number of photons emitted by a red bulb and a blue bulb of equal power in a given time. Then:
1. \(n_r=n_b\)
2. \(n_r<n_b\)
3. \(n_r>n_b\)
4. the information is insufficient to get a relation between \(n_r\) and \(n_b\)
Subtopic:  Particle Nature of Light |
 68%
Level 2: 60%+
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