Q. No.In the photoelectric effect electromagnetic wave is incident on a metal surface and electrons are ejected from the surface. If the work function of the metal is \(2.14~\text{eV}\) and stopping potential is \(2~\text{V},\) what is the wavelength of the electromagnetic wave?
1. \(400~\text{nm}\)
2. \(300~\text{nm}\)
3. \(600~\text{nm}\)
4. \(200~\text{nm}\)
1. \(400~\text{nm}\)
2. \(300~\text{nm}\)
3. \(600~\text{nm}\)
4. \(200~\text{nm}\)
Subtopic: Photoelectric Effect: Experiment |
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Level 2: 60%+
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In an experiment with photoelectric effect, the stopping potential:
| 1. | increases with increase in the intensity of the incident light |
| 2. | decreases with increase in the intensity of the incident light |
| 3. | increases with increase in the wavelength of the incident light |
| 4. | is \(\left(\dfrac{1}{e}\right)\) times the maximum kinetic energy of the emitted photoelectrons |
Subtopic: Photoelectric Effect: Experiment |
Level 4: Below 35%
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Given below are two statements:
In the light of the above statements, choose the most appropriate answer from the options given below:
| Assertion (A): | Emission of electrons in photoelectric effect can be suppressed by applying a sufficiently negative electron potential to the photo emissive substance. |
| Reason (R): | A negative electric potential, which stops the emission of electrons from the surface of a photo emissive substance, varies linearly with frequency of incident radiation. |
| 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 False but (R) is True |
| 4. | (A) is True but (R) is False |
Subtopic: Photoelectric Effect: Experiment |
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Cesium \((\mathrm{Cs})\) and lithium \((\mathrm{Li})\) have work functions of \(1.9 ~\text {eV}\) and \(2.5~\text {eV},\) respectively. If light of wavelength \(550~ \text {nm} \) is incident on both metal surfaces, for which metal(s) will the photoelectric effect occur?
1. Both \(\mathrm{Cs}\) and \(\mathrm{Li}\)
2. neither \(\mathrm{Cs}\) nor \(\mathrm{Li}\)
3. \(\mathrm{Cs}\) only
4. \(\mathrm{Li}\) only
1. Both \(\mathrm{Cs}\) and \(\mathrm{Li}\)
2. neither \(\mathrm{Cs}\) nor \(\mathrm{Li}\)
3. \(\mathrm{Cs}\) only
4. \(\mathrm{Li}\) only
Subtopic: Photoelectric Effect: Experiment |
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Level 2: 60%+
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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
|
| 2. |
Both A and R are correct and R is the correct explanation of A
|
| 3. |
A is correct but R is not correct
|
| 4. |
A is not correct but R is correct.
|
Subtopic: Photoelectric Effect: Experiment |
85%
Level 1: 80%+
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In the photoelectric effect, which graph correctly shows how photocurrent \((i) \) varies with stopping potential \((V_s)\) when light of the same frequency but two different intensities \((I_1>I_2)\) is used?
| 1. |  |
2. |  |
| 3. |  |
4. |  |
Subtopic: Photoelectric Effect: Experiment |
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The work functions of two metals are \(9~\text{eV}\) and \(4.5~\text{eV},\) respectively. What is the approximate difference between their threshold wavelengths? \((\text{use}~hc=1240~\text{eV-nm})\)
| 1. | \(138~\text{nm}\) | 2. | \(130~\text{nm}\) |
| 3. | \(112~\text{nm}\) | 4. | \(145~\text{nm}\) |
Subtopic: Photoelectric Effect: Experiment |
78%
Level 2: 60%+
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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. |
Subtopic: Photoelectric Effect: Experiment |
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Level 1: 80%+
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An electron with speed \(v\) and a photon with speed \(c\) have the same de-Broglie wavelength. If the kinetic energy and momentum of the electron are \(E_e\) and \(\rho_e\) and that of photon are \(E_{ph}\) and \(\rho_{ph}\) respectively. Which of the following is correct?
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. \( \frac{p_{e}}{p_{ph}}=\frac{v}{2 c}\)
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. \( \frac{p_{e}}{p_{ph}}=\frac{v}{2 c}\)
Subtopic: Photoelectric Effect: Experiment | De-broglie Wavelength |
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Given below are two statements:
| 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. |
Subtopic: Photoelectric Effect: Experiment |
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Level 1: 80%+
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