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Q. No.Radiation with wavelength \(\lambda\) is incident on a photocell, causing the fastest emitted electron to have a speed \(v.\) If the wavelength is changed to \(\dfrac{3\lambda}{4},\) what will be the speed of the fastest emitted electron?
1. \( >v\left(\dfrac{4}{3}\right)^{\frac{1}{2}} \)
2. \( <v\left(\dfrac{4}{3}\right)^{\frac{1}{2}} \)
3. \( =v\left(\dfrac{4}{3}\right)^{\frac{1}{2}} \)
4. \( =v\left(\dfrac{3}{4}\right)^{\frac{1}{2}}\)
An electron beam is accelerated by a potential difference \(V\) to hit a metallic target to produce \({X}\)-ray. It produces continuous as well as characteristic \({X}\)-rays. If \(\lambda_{\text{min}}\) is the smallest possible wavelength of \({X}\)-ray in the spectrum, the variation of \(\log \lambda_{\text{min}}\) with \(\log V\) is correctly represented in:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
The figure shows the stopping potential \(V_0\) (in volts), as a function of frequency \(\nu,\) for a sodium emitter. From the data plotted in the graph, what is the work function of sodium?
(Given: Planck’s constant, \(h=\) \(6.63\times 10^{-34}~\text{J-s}\) and the charge of an electron, \(e=1.6\times 10^{-19}~\text{C}\))
| 1. | \(1.95~\text{eV}\) | 2. | \(2.12~\text{eV}\) |
| 3. | \(1.82~\text{eV}\) | 4. | \(1.66~\text{eV}\) |
| 1. | The slope of the straight line gets steeper. |
| 2. | The straight line shifts to the right. |
| 3. | The graph does not change. |
| 4. | The straight line shifts to the left. |
1. \(\frac{E_e}{E_{p h}}=\frac{2 c}{v} \)
2. \(\frac{E_e}{E_{p h}}=\frac{v}{2 c} \)
3. \( \frac{{p}_{e}}{{p}_{ph}}=\frac{2{c}}{{v}} \)
4. \( \frac{p_{e}}{p_{ph}}=\frac{v}{2 c}\)
| Assertion (A): | The photoelectric effect does not take place if the energy of the incident radiation is less than the work function of a metal. |
| Reason (R): | Kinetic energy of the photoelectrons is zero if the energy of the incident radiation is equal to the work function of a metal. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
| (A) | The square of the maximum velocity of photoelectrons varies linearly with the frequency of the incident light. |
| (B) | The saturation current increases when the light source is moved farther away from the metal surface. |
| (C) | The maximum kinetic energy of photoelectrons decreases when the power (intensity) of the LED source is reduced. |
| (D) | The immediate emission of photoelectrons from the metal surface cannot be explained by the particle nature of light. |
| (E) | The existence of a threshold wavelength cannot be explained by the wave nature of light. |
Which of the following options correctly identifies the true statements?
| 1. | (A) and (B) only | 2. | (A) and (E) only |
| 3. | (C) and (E) only | 4. | (D) and (E) only |
Which of the following statements correctly describes the photoelectric effect?
| 1. | The maximum kinetic energy of emitted electrons depends on the intensity of light. |
| 2. | The stopping potential depends only on the work function of the metal. |
| 3. | The photoelectric effect can be explained using the wave nature of light. |
| 4. | The photoelectric effect is best explained by the particle nature of light. |
| 1. | \(138~\text{nm}\) | 2. | \(130~\text{nm}\) |
| 3. | \(112~\text{nm}\) | 4. | \(145~\text{nm}\) |
Given below are two statements :
| Assertion A: | Number of photons increases with increase in frequency of light. |
| Reason R: | Maximum kinetic energy of emitted electrons increases with the frequency of incident radiation. |
Choose the most appropriate answer from the options given below :
| 1. |
Both A and R are correct and R is not the correct explanation of A
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| 2. |
Both A and R are correct and R is the correct explanation of A
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| 3. |
A is correct but R is not correct
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| 4. |
A is not correct but R is correct.
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