Physics M.C.Q (1 Marks)

If two + 5 D lenses are mounted at some distance apart, the equivalent power will always be negative if the distance is

Figure given below shows a beam of light converging at point P. When a convex lens of focal length 16 cm is introduced in the path of the beam at a place O shown by dotted line such that OP becomes the axis of the lens, the beam converges at a distance x from the lens. The value x will be equal to

The unit of focal power of a lens is

A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are joined together. The power of the combination will be

A convex lens forms a real image of an object for its two different positions on a screen. If height of the image in both the cases be 8 cm and 2 cm, then height of the object is
 

The combination of a convex lens (f = 18 cm) and a thin concave lens (f = 9 cm) is

An object has image thrice of its original size when kept at 8 cm and 16 cm from a convex lens. Focal length of the lens is

A convex lens has a focal length f. It is cut into two parts along the dotted line as shown in the figure. The focal length of each part will be

The focal length of a convex lens is 10 cm and its refractive index is 1.5. If the radius of curvature of one surface is 7.5 cm, the radius of curvature of the second surface will be

In a plano-convex lens the radius of curvature of the convex lens is 10 cm. If the plane side is polished, then the focal length will be (Refractive index = 1.5)

A candle placed 25 cm from a lens, forms an image on a screen placed 75 cm on the other end of the lens. The focal length and type of the lens should be

Chromatic aberration of lens can be corrected by

The distance between an object and the screen is 100 cm. A lens produces an image on the screen when placed at either of the positions 40 cm apart. The power of the lens is

An object is placed first at infinity and then at 20 cm from the object side focal plane of the convex lens. The two images thus formed are 5 cm apart. The focal length of the lens is

A thin lens made of glass of refractive index 1.5 has a front surface + 11 D power and back surface – 6 D. If this lens is submerged in a liquid of refractive index 1.6, the resulting power of the lens is

A convex lens has 9 cm focal length and a concave lens has – 18 cm focal length. The focal length of the combination in contact will be

A lens which has focal length of 4 cm and refractive index of 1.4 is immersed in a liquid of refractive index 1.6, then the focal length will be

A lens of focal power 0.5 D is

A double convex lens of glass of m = 1.5 has radius of curvature of each of its surface is 0.2 m. The power of the lens is

A convex lens of power + 6D is placed in contact with a concave lens of power – 4D. What is the nature and focal length of the combination

A convex lens is used to form real image of an object on a screen. It is observed that even when the positions of the object and that screen are fixed there are two positions of the lens to form real images. If the heights of the images are 4 cm and 9 cm respectively, the height of the object is

A concave lens of focal length 20 cm placed in contact with a plane mirror acts as a

A substance is behaving as convex lens in air and concave in water, then its refractive index is

Two thin lenses whose powers are +2D and –4D respectively combine, then the power of combination is

If a lens is cut into two pieces perpendicular to the principal axis and only one part is used, the intensity of the image

If a convex lens of focal length 80 cm and a concave lens of focal length 50 cm are combined together, what will be their resulting power

Focal length of a convex lens of refractive index 1.5 is 2 cm. Focal length of lens when immersed in a liquid of refractive index of 1.25 will be

Focal length of a converging lens in air is R. If it is dipped in water of refractive index 1.33, then its focal length will be around (Refractive index of lens material is 1.5)

The focal length of a combination of lenses formed with lenses having powers of + 2.50 D and – 3.75 D will be

A convex lens

A biconvex lens with equal radii curvature has refractive index 1.6 and focal length 10 cm. Its radius of curvature will be

A achromatic combination is made with a lens of focal length f and dispersive power ω with a lens having dispersive power of 2ω. The focal length of second will be

The image distance of an object placed 10 cm in front of a thin lens of focal length + 5 cm is

An achromatic combination of lenses is formed by joining

A double convex lens is made of glass of refractive index 1.5. If its focal length is 30 cm, then radius of curvature of each of its curved surface is

A convex lens of focal length 0.5 m and concave lens of focal length 1 m are combined. The power of the resulting lens will be

A concave lens of glass, refractive index 1.5, has both surfaces of same radius of curvature R. On immersion in a medium of refractive index 1.75, it will behave as a

A plane convex lens is made of refractive index 1.6. The radius of curvature of the curved surface is 60 cm. The focal length of the lens is

A symmetric double convex lens is cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power of a cut lens will be

An object of height 1.5 cm is placed on the axis of a convex lens of focal length 25 cm. A real image is formed at a distance of 75 cm from the lens. The size of the image will be

An equiconvex lens of glass of focal length 0.1 metre is cut along a plane perpendicular to principle axis into two equal parts. The ratio of focal length of new lenses formed is

The plane surface of a plano-convex lens of focal length f is silvered. It will behave as

The dispersive powers of glasses of lenses used in an achromatic pair are in the ratio 5 : 3. If the focal length of the concave lens is 15 cm, then the nature and focal length of the other lens would be