Objects on the other side of _________ objects can not be seen at all.

if n objects are arranged in a row then the number of ways of selecting three of these objects so that no two of them are next to each other is

A convex lens produces a real image double the size of the object, when the object is placed at a distance 18 cm from it. Where should the object be placed to produce a real image three times the size of the object?

An object is placed in front of a convex lens at a distance twice of focal length.A concave mirror is on the other side of the lens. The distance between lens and mirror is twice of the sum of their focal length.Find image distance, nature of image and the magnification.

Algal bloom can be seen for-

A plane mirror can form a real image of a ________ object [Fill in blanks].

A luminous object________

Nephropathy can be seen in case of

An object is placed at a distance of 50cm is front of a convex mirror. Now a plane mirror is placed in between the object and the convex mirror, converting the lower half of the convex mirror. If the distance of the plane mirror from the object is 30cm, it is seen that there is no parallax of the images formed by the two mirrors. What is the radius of curvature of the convex mirror?

An object is placed at a distance of 20 cm in front of a convex mirror. Now a plane mirror is placed in between the object and the convex mirror, convering the lower half of the convex mirror, If the distance of the plane mirror from the object is 15 cm, it is seen that the images formed by the two mirrors coincide. Determine the radius of curvature of the convex mirror.