The minimum distance between an object and its real image in a convex lens is_____________?

A. 2 f
B. 2.5 f
C. 3f
D. 4f

Dioptre power of an concave lens of 10 cm focal length is_______________?

A. 10 dioptre
B. 10 dioptre
C. 1 / 10 dioptre
D. 1 / 10 dioptre

A point where the incident parallel rays of light converge or appear to diverge after passing through a lens is called______________?

A. Center of curvature
B. Focus
C. Optical center
D. Aperture

If an object is placed away from 2f of a converging lens then the image will be_______________?

A. Real and erect
B. Virtual and erect
C. Real and inverted
D. Virtual

Magnifying power of simple microscope______________?

A. Increase with increase in focal length
B. Increase with decrease in focal length
C. No effect with decrease or increase with focal length
D. List distance of distinct vision

The least distance of distinct vision for a normal eye is_______________?

A. 15 cm
B. 25 cm
C. 30 cm
D. 40 cm

If a convex lens of large aperture fails to converge the light rays incident on it to a single point, it is said to suffer from______________?

A. Chromatic aberration
B. Spherical aberration
C. Both spherical and chromatic
D. Distortion

A convex lens of focal length f1 and a concave lens of focal length f2 are placed in contact. The focal length of the combination is_____________?

A. F2 + f1
B. F2 – f1
C. F1f2/f2+f1
D. F1f2/f1-f2

In multimode step index fibre the refractive index of core and cladding is____________?

A. Same
B. Different
C. Zero
D. Different with refractive index of core higher than cladding

Final image produced by a compound microscope is_____________?

A. Real and inverted
B. Real and erect
C. Virtual and erect
D. Virtual and inverted