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+f1D. f1f2/f1-f2
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 aberrationB. spherical aberration C. both spherical and chromatic D. distortion
The least distance of distinct vision for a normal eye is_______________? A. 15 cmB. 25 cm C. 30 cm D. 40 cm
Magnifying power of simple microscope______________? A. increase with increase in focal lengthB. increase with decrease in focal length C. no effect with decrease or increase with focal length D. list distance of distinct vision
If an object is placed away from 2f of a converging lens then the image will be_______________? A. real and erect B. virtual and erectC. real and inverted D. virtual
The power of a concave lens is_______________? A. real B. virtual C. positiveD. negative
Unit of power of a lens is________________? A. meter B. wattC. diopter D. horsepower
The diameter of a lens is called________________? A. focal lengthB. principal axis C. aperture D. radius of curvature
A lens which converges a beam of parallel rays to a point is called______________? A. diverging (or concave) lensB. converging (or convex) lens C. plano concave lens D. plano convex lens