Ray Optics Test...

Focal length of a convex lens will be maximum for

A boy is trying to start a fire by focusing Sunlight on a piece of paper using an equiconvex lens of focal length 10 cm. The diameter of the Sun is 1.39 × 10⁹ m and its means distance from the earth is 1.5 × 10¹¹ m. What is the diameter of the Sun\'s image on the paper?

A combination of two thin lenses with focal lengths f₁ and f₂ respectively forms an image of distant object at distance 60 cm when lenses are in contact. The position of this image shifts by 30 cm towards the combination when two lenses are separated by 10 cm. The corresponding values of f₁ and f₂ are

An achromatic combination of lenses is formed by joining

A plano convex lens (f = 20 cm) is silvered at plane surface. Now f will be

A diminished image of an object is to be obtained on a screen 1.0 m from it. This can be achieved by appropriately placing

The focal length of convex lens is 30 cm and the size of image is quarter of the object, then the object distance is

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, the image will

A lens (focal length 50 cm) forms the image of a distant object which subtends an angle of 1 milli radian at the lens. What is the size of the image?

Two thin lenses of focal lengths f₁ and f₂ are in contact and coaxial. The combination is equivalent to a singlelens of power