A thin lens of focal length 10 cm is cut into two equal halves and is kept as shown in the figure. If an object O is placed at a distance 10 cm from the optical centre of combination, then the distance of the image from the object will be
(1) 5 cm
(2) 7.5 cm
(3) 10 cm
(4) 20 cm
If a glass prism of refractive index 1.5 dipped in a liquid having refractive index same as that of the material of prism, then the dispersive power of prism will
(1) Become zero
(2) Increase
(3) Remain same
(4) Depend on apex angle of prism
A concave and convex lens has the same focal length of 20 cm and are put into contact to form a lens combination. The combination is used to view an object of 5 cm length kept at 20 cm from the lens combination. As compared to the object, the image will be
1. Of the same size as the object and erect
2. Of the same size as the object but inverted
3. magnified and inverted
4. Reduced and erect
What should be the angle between two plane mirror, if an object placed symmetrically between them has five images?
(1) 75
(2) 60
(3) 120
(4) 59
The maximum magnification which can be obtained with the help of a simple microscope is 6. If a point object is placed at distance 3 cm from the microscope, then what was be the position of the image?
(1) -7.5 cm
(2) -6.4 cm
(3) 8.2 cm
(4) 5.45 cm
A converging spherical wavefront is obtained from
(1) Light emerging from a convex lens when a point source is placed at its focus
(2) A parallel beam of light incident on the convex lens
(3) Light converging at a point
(4) Both (2) & (3)
A concave lens of glass of refractive index 1.5 has both surfaces of the same radius of curvature R. On immersion in a medium of refractive index 1.75, it will have as a
1. Divergent lens of focal length 3R
2. Divergent lens of focal length 4R
3. Convergent lens of focal length 3.5R
4. Convergent lens of focal length 5R
A ray is incident normally on a right-angled prism whose R.I is and prism angle . Deviation to the ray is equal to
(1)
(2)
(3)
(4) 2
A convex lens forms the image of a point object \(O\) on the screen. If a glass slab of thickness 3 cm and refractive index 1.5 is put as shown below, then to have the image of the object on the screen, the object should be shifted:
1. | away from the lens by 1 cm |
2. | away from the lens by 1.5 cm |
3. | towards the lens by 1 cm |
4. | towards the lens by 1.5 cm |
Two convex lenses of focal lengths are separated co-axially by a distance d. The power of the combination will be zero if d equals to
1.
2.
3.
4.