Q. No.For a parallel beam of monochromatic light of wavelength \(\lambda\), diffraction is produced by a single slit whose width \(a\) is much greater than the wavelength of the light. If \(D\) is the distance of the screen from the slit, the width of the central maxima will be:
1.
\(\dfrac{2D\lambda}{a}\)
2.
\(\dfrac{D\lambda}{a}\)
3.
\(\dfrac{Da}{\lambda}\)
4.
\(\dfrac{2Da}{\lambda}\)
Given below are two statements:
| Assertion (A): | It is not possible to have interference between the waves produced by two violins. |
| Reason (R): | For interference of two waves the phase difference between the waves must remain constant.Given below are two statements. |
| 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. |
The equations of two light waves are given by:
\(y_1=6~\text{cos}(\omega t)\) & \(y_2=8~\text{cos}(\omega t+\phi).\)
What is the ratio of the maximum to the minimum intensities produced by the superposition of these waves?
1. \(49:1\)
2. \(1:49\)
3. \(1:7\)
4. \(7:1\)
| 1. | \(\dfrac{\sqrt{n}}{n+1}\) | 2. | \(\dfrac{2\sqrt{n}}{n+1}\) |
| 3. | \(\dfrac{\sqrt{n}}{(n+1)^2}\) | 4. | \(\dfrac{2\sqrt{n}}{(n+1)^2}\) |
In Lloyd's mirror experiment, we generate one source by reflection because we need sources:
1. producing light of the same intensities
2. producing light of the same wavelength
3. coherent in nature
4. incoherent in nature
In Young's double-slit experiment, the intensity of light due to each slit is \(I_0.\) An interference pattern is observed on a screen \(S,\) placed parallel to the line joining the slits \(S_1\) and \(S_2.\)
What are the values of minimum, maximum, and average intensities over the entire screen?
1. \(0, 4I_0, 2I_0\)
2. \(0, 4I_0, I_0\)
3. \(I_0, 2I_0, \dfrac{3I_0}{2}\)
4. \(0, 2I_0, I_0\)
The angular width of the central maximum in the Fraunhofer diffraction for \(\lambda=6000~{\mathring{A}}\) is \(\theta_0.\) When the same slit is illuminated by another monochromatic light, the angular width decreases by \(30\%.\) The wavelength of this light is:
1. \(1800~{\mathring{A}}\)
2. \(4200~{\mathring{A}}\)
3. \(420~{\mathring{A}}\)
4. \(6000~{\mathring{A}}\)
In Young's double slit experiment, a slit is covered with a thin film so that the optical path difference introduced between coherent waves is . Then the new position of central maxima will be at
1. The initial position of 5th maxima
2. The initial position of 3rd minima
3. The initial position of 2nd minima
4. The initial position of 3rd maxima
A diffraction pattern is obtained by using a beam of red light. What will happen, if the red light is replaced by blue light?
1. Bands will become narrower
2. Bands become broader
3. No change will take place
4. Bands disappear
1. half
2. four times
3. one-fourth
4. double
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