Q. No.| Assertion (A): | The work function of aluminium is \(4.2~\text{eV}\). Emission of electrons will not be possible if two photons, each of energy \(2.5~\text{eV}\), strike an electron of aluminium. |
| Reason (R): | For photoelectric emission, the energy of each photon should be greater than the work function of aluminium. |
| 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. | Both (A) and (R) are False. |
(Take \(h=6.6\times 10^{-34}\ \) J-s)
1. \(B\) only
2. \(A\) only
3. neither \(A\) nor \(B\)
4. both \(A\) and \(B\)
1. orange light
2. yellow light
3. green light
4. violet light
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
| 1. | four times, doubled |
| 2. | doubled, remains unchanged |
| 3. | remains unchanged, doubled |
| 4. | four times, remains unchanged |
When the intensity of a light source is increased,
| (a) | the number of photons emitted by the source in unit time increases. |
| (b) | the total energy of the photons emitted per unit time increases. |
| (c) | more energetic photons are emitted. |
| (d) | faster photons are emitted. |
Choose the correct option:
| 1. | (a), (b) | 2. | (b), (c) |
| 3. | (c), (d) | 4. | (a), (d) |
A photo-cell is illuminated by a source of light, which is placed at a distance \(d\) from the cell. If the distance becomes \(\dfrac{d}{2}\), then the number of electrons emitted per second will be:
1. same
2. four times
3. two times
4. one-fourth
A point source of light is used in a photoelectric effect. If the source is removed farther from the emitting metal, the stopping potential:
| 1. | will increase. |
| 2. | will decrease. |
| 3. | will remain constant. |
| 4. | will either increase or decrease. |
If stopping potential \(V_{0}\) is plotted versus frequency \(\nu\) in an experiment of the photoelectric effect, the graph as shown in the diagram is obtained. Then: (e is an electronic charge)
| 1. | Planck's constant = \(\dfrac{b}{a}\) |
| 2. | Planck's constant = \(\dfrac{eb}{a}\) |
| 3. | Planck's constant = \(\dfrac{a}{b}\) |
| 4. | Planck's constant = \(\dfrac{ea}{b}\) |
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