Optics (Test 1)

A convex lens of focal length 30 cm is placed in contact with a concave lens of focal length 20 cm. An object is placed at 20 cm to the left of this lens system. The distance of the image from the lens is:

A concave-convex lens has refractive index 1.5 and radii of curvature 30 cm and 20 cm. The concave surface is filled with liquid of refractive index 1.3. The focal length of the combination is:

A mirror produces an image with magnification 1/4. If the distance between object and image is 40 cm, the focal length of the mirror is:

Two thin convex lenses of focal lengths 30 cm and 10 cm are placed coaxially, 10 cm apart. The power of the combination is:

A lens of refractive index 1.6 has focal length 12 cm in air. Find its focal length in water (μ = 1.28):

A convex mirror of focal length 30 cm forms an image coinciding with that of a plane mirror placed behind it. The object is 30 cm in front of the convex mirror. The distance between the mirrors is:

An object is placed 40 cm from a spherical mirror and an image of magnification 1/2 is produced. To get magnification 1/3, the object should be moved:

The radii of curvature of a thin convex lens are 10 cm and 15 cm. The focal length is 12 cm. The refractive index of the lens material is:

Two identical objects are placed in front of a convex and concave mirror with same radius of curvature 12 cm, at 18 cm distance. The ratio of image sizes is:

A bi-convex lens has radius of curvature 1/6 cm. To replace it with a lens of unequal radii but same power, possible combination of R₁ and R₂ is: