Q. No.About \(5\)% of the power of a \(100\) W light bulb is converted to visible radiation. What is the average intensity of visible radiation at a distance of \(1\) m from the bulb?
1. \(0.472\) W/m2
2. \(0.398\) W/m2
3. \(0.323\) W/m2
4. \(0.401\) W/m2
Light of wavelength 488 nm is produced by an argon laser which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the stopping (cut-off) potential of photoelectrons is 0.38 V. Find the work function of the material from which the emitter is made.
1. 2.16 eV
2. 3.06 eV
3. 2.0 eV
4. 0.38 eV
What will be the momentum, of the electrons accelerated through a potential difference of 56 V.
1. \(4.07 \times 10^{-25} \mathrm{~kg} \mathrm{~ms^{-1 }}\)
2. \(4.04 \times 10^{-24} \mathrm{~kg} \mathrm{~ms}^{-1}\)
3. \(4.07 \times 10^{-24} \mathrm{~kg} \mathrm{~ms^{-1 }}\)
4. \(4.04 \times 10^{-25} \mathrm{~kg} \mathrm{~ms}^{-1}\)
What is the de-Broglie wavelength of an electron with the kinetic energy of \(120\) eV?
1. \(0.123\) nm
2. \(0.121\) nm
3. \(0.112\) nm
4. \(0.131\) nm
For what kinetic energy of a neutron will the associated de Broglie wavelength be
1.40 x m?
1.\(1.1 \times 10^{-2}\ eV\)
2.\(2.1 \times 10^{-2}\ eV\)
3.\(3.3 \times 10^{-2}\ eV\)
4.\(4.2 \times 10^{-2}\ eV\)
What is the de Broglie wavelength of a nitrogen molecule in air at 300 K? Assume that the molecule is moving with the root-mean-square speed of molecules at this temperature. (Atomic mass of nitrogen = 14.0076 u)
1. 0.028 nm
2. 0.031 nm
3. 0.127 nm
4. 0.0139 nm
What is the de-Broglie wavelength of a bullet of mass \(0.040\) kg traveling at the speed of \(1.0\) km/s?
| 1. | \(1.65\times10^{-35}\) m | 2. | \(1.05\times10^{-35}\) m |
| 3. | \(2.15\times10^{-35}\) m | 4. | \(2.11\times10^{-35}\) m |
An electron and a photon each have a wavelength of 1.00 nm. The momentum of the electron will be:
1. Greater than photon.
2. Equal to the photon.
3. Less than photon.
4. None of these.
The work function of cesium metal is \(2.14\) eV. When light of frequency \(6\times10^{14}\) Hz is incident on the metal surface, photoemission of electrons occurs. What is the stopping potential of the metal?
| 1. | \(0.212\) V | 2. | \(0.345\) V |
| 3. | \(0.127\) V | 4. | \(0.311\) V |
The photoelectric cut-off voltage in a certain experiment is \(1.5~\text{V}\). What is the maximum kinetic energy of photoelectrons emitted?
| 1. | \(2.1 \times 10^{-19}~\text{J} \) | 2. | \(1.7 \times 10^{-19}~\text{J} \) |
| 3. | \(2.4 \times 10^{-19}~\text{J} \) | 4. | \(1.1 \times 10^{-19}~\text{J} \) |
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