Q. No.Electrons used in an electron microscope are accelerated by a voltage of \(25\) kV. If the voltage were increased to \(100\) kV, then the de-Broglie wavelength associated with the electrons would:
1.
decrease by \(2\) times
2.
decrease by \(4\) times
3.
increase by \(4\) times
4.
increase by \(2\) times
| 1. | decrease by \(2\) times |
| 2. | decrease by \(4\) times |
| 3. | increase by \(4\) times |
| 4. | increase by \(2\) times |
| 1. | \(1.00\) | 2. | \(1.02\) |
| 3. | \(1.04\) | 4. | \(0.98\) |
1. \(5\times 10^{15}\)
2. \(5\times 10^{16}\)
3. \(5\times 10^{17}\)
4. \(5\times 10^{14}\)
When photons of energy \(h\nu\) fall on an aluminium plate (of work function \(E_0\)), photoelectrons of maximum kinetic energy \(K\) are ejected.
If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be:
1. \(K+ E_0\)
2. \(2K\)
3. \(K\)
4. \(K + h\nu\)
In an experiment of the photoelectric effect, the wavelength of incident radiation is . The wavelength of incident radiation is reduced to rd of initial value and the maximum kinetic energy of photoelectron is observed to be n times the previous value. What will be the threshold wavelength for the metal plate?
| 1. | \(\dfrac{n-1}{n-3} \lambda \) | 2. | \(\dfrac{n}{n-3} \lambda \) |
| 3. | \(\dfrac{n-3}{n-1} \lambda \) | 4. | \(\dfrac{n+1}{n-3} \lambda\) |
1. \(0.25~\mathring{A}\)
2. \(0.5~\mathring{A}\)
3. \(1.5~\mathring{A}\)
4. \(2~\mathring{A}\)
| 1. | four times | 2. | one-fourth |
| 3. | zero | 4. | doubled |
An electron is accelerated from rest through a potential difference of \(V\) volt. If the de Broglie wavelength of an electron is \(1.227\times10^{-2}~\text{nm}.\) What will be its potential difference?
| 1. | \(10^{2}~\text{V}\) | 2. | \(10^{3}~\text{V}\) |
| 3. | \(10^{4}~\text{V}\) | 4. | \(10^{5}~\text{V}\) |
1. \(1.3\) V
2. \(0.5\) V
3. \(2.3\) V
4. \(1.8\) V
1. \(1.5\times 10^{20}\)
2. \(6\times 10^{18}\)
3. \(62\times 10^{20}\)
4. \(3\times 10^{19}\)
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