The distance between the object and its real image formed by a concave mirror is minimum when the distance of the object from the centre of curvature of the mirror is: [f focal length of the mirror]
1. Zero
2.
3. f
4. 2f
Two slabs P & Q of transparent materials have a thickness in the ratio 2 : 5. If a ray of light takes the same amount of time to move from A to B and B to C, then the refractive index of Q with respect to P will be:
1. 0.4
2. 2.5
3. 1.4
4. 1.85
In the following diagram, what is the distance x if the radius of curvature is R = 15 cm?
1. 30 cm
2. 20 cm
3. 15 cm
4. 10 cm
In the diagram shown below, the image of the point object O is formed at \(l\) by the convex lens of focal length 20 cm, where \(F_1\) and \(F_2\) are foci of the lens. The value of \(x'\) is:
1. | 10 cm | 2. | 20 cm |
3. | 30 cm | 4. | 40 cm |
If the space between two convex lenses of glass in the combination shown in the figure below is filled with water, then:
1. | the focal length of the system will decrease. |
2. | the focal length of the system will increase. |
3. | the power of the system will increase. |
4. | the power of the system will become infinite. |
Focal lengths of objective and eyepiece of a compound microscope are 2 cm and 6.25 cm respectively. An object AB is placed at a distance of 2.5 cm from the objective which forms the image A'B' as shown in the figure. Maximum magnifying power in this case, will be:
1. | 10 | 2. | 20 |
3. | 5 | 4. | 25 |
A concave lens of focal length 25 cm produces an image the size of the object. The distance of the object from the lens is:
1. 225 cm
2. 250 cm
3. 150 cm
4. 175 cm
A mark on the surface of sphere (µ = 3/2) is viewed from a diametrically opposite position. It appears to be at a distance \(15~\mathrm{cm}\) from its actual position. The radius of sphere is:
1. 15 cm
2. 5 cm
3. 7.5 cm
4. 2.5 cm
Choose the correct mirror image of the figure:
1. | 2. | ||
3. | 4. |
A lens forms an image of a point object placed at distance 20 cm from it. The image is formed just in front of the object at a distance 4 cm from the object (and towards the lens). The power of the lens is:
1. 2.25 D
2. 1.75 D
3. 1.25 D
4. 1.4 D