Q. No.| 1. | \(P_1+P_2\) | 2. | \(|P_1-P_2|\) |
| 3. | \({\Large\frac{P^2_1}{P_2}}\) | 4. | \({\Large\frac{P^2_2}{P_1}}\) |
A convex lens forms a real image of a point object placed on its principal axis. If the upper half of the lens is painted black,
| a. | the image will be shifted downward |
| b. | the image will be shifted upward |
| c. | the image will not be shifted |
| d. | the intensity of the image will decrease |
Choose the correct option:
| 1. | (a) and (b) |
| 2. | (b) and (c) |
| 3. | (c) and (d) |
| 4. | all of these |
If \(f=0.5~\text m\) for a glass lens, what is the power of the lens?
1. \(+0.4~\text D\)
2. \(+4.0~\text D\)
3. \(+0.2~\text D\)
4. \(+2.0~\text D\)
A convex lens is used to form an image of an object on a screen. If the upper half of the lens is blackened so that it becomes opaque, then:
| 1. | only half of the image will be visible. |
| 2. | the image position shifts towards the lens. |
| 3. | the image position shifts away from the lens. |
| 4. | the brightness of the image reduces. |
A thin, symmetric double-convex lens with a power \(P\) is cut into three parts: \(A, B\) and \(C,\) as shown in the figure.
The following statements describe the powers of the sections:
| (A) | The power of \(A\) is \(P.\) |
| (B) | The power of \(A\) is \(2P.\) |
| (C) | The power of \(B\) is \(\Large\frac P 2\). |
| (D) | The power of \(B\) is \(\Large\frac P 4\). |
Choose the correct option from the given ones:
| 1. | (A), (B) and (C) only |
| 2. | (A) and (C) only |
| 3. | (B) and (D) only |
| 4. | (B), (C) and (D) only |
| 1. | \(m\) | 2. | \(\frac{1}{m}\) |
| 3. | \(m+1\) | 4. | \(\frac{1}{{m}{+}{1}}\) |
Two convex lenses of focal lengths \(10~\text{cm}\) and \(30~\text{cm}\) are kept in contact. Then the correct statement is:
| 1. | the effective focal length is \(15~\text{cm}\). |
| 2. | the effective focal length is \(7.5~\text{cm}\). |
| 3. | combination behaves like a divergent lens. |
| 4. | all of these. |
| 1. | \(8~\text{cm}\) | 2. | \(20.3~\text{cm}\) |
| 3. | \(13.3~\text{cm}\) | 4. | \(16~\text{cm}\) |
| 1. | \(P=P_1+P_2+\dfrac{1}{d}\) | 2. | \(\dfrac{1}{P}=\dfrac{1}{P_1}+\dfrac{1}{P_2}+\dfrac{1}{d}\) |
| 3. | \(P=P_1+P_2+dP_1P_2\) | 4. | \(P=P_1+P_2-dP_1P_2\) |
A symmetric double convex lens is cut in two equal parts by a plane containing the principal axis. If the power of the original lens was \(4~\text{D},\) the power of a divided lens will be:
1. \(2~\text{D}\)
2. \(3~\text{D}\)
3. \(4~\text{D}\)
4. \(5~\text{D}\)
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