A \(5\) W emits monochromatic light of wavelength \(5000~\mathring{A}\). When placed \(0.5\) m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved \(1.0\) m away, the number of photoelectrons liberated is reduced by a factor of?
1. \(4\)
2. \(8\)
3. \(16\)
4. \(2\)

Subtopic:  Electron Emission |
 71%
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AIPMT - 2007
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A photocell is receiving light from a source placed at a distance of \(1\) m. If the same source is placed at a distance of \(2\) m, then the ejected electron:
1. moves with one-fourth of energy as that of the initial energy.
2. moves with one-fourth of momentum as that of the initial momentum.
3. will be half in number.
4. will be one-fourth in number.
Subtopic:  Electron Emission |
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Consider a beam of electrons (each electron with energy \(E_0)\) incident on a metal surface kept in an evacuated chamber. Then:

1. no electrons will be emitted as only photons can emit electrons.
2. electrons can be emitted but all with energy, \(E_0\).
3. electrons can be emitted with any energy, with a maximum of \(\mathrm{E}_0-\phi\) (\(\phi\) is the work function).
4. electrons can be emitted with any energy, with a maximum \(E_0\).
Subtopic:  Electron Emission |
From NCERT
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