A thin rod of length (f/3) is placed along the principal axis of a concave mirror of focal length f such that its image, which is real and elongated, just touches the rod. What is the magnification?

An object is held at the principal focus of a concave lens of focal length F. where is the image formed?

A short linear object of length b lies along the axis of a concave mirror of focal length f at a distance u from the pole. What is the size of the image?

An object of 3 cm length is placed at 10 cm from the ple of a concave irror of focal length 9 cm.Find the size and position of the image.

A 5 cm long needle lies along the principal axis axis of a concave miror of focal length 20 cm in such a way that the end closer to the pole is 40 cm from it.Find the length of the image of the needle formed by the mirror.

Find the position of an object,which when placed in front of a concave mirror of focal length 20 cm,produces a virtual image,which is twice the size of the object.

If a concave mirror of focal length f produces a real image n times the size of the object,then find the distance of the object from the mirror.

A concave mirror of focal length f ( in air ) is immersed in water (mu=4//3) .The focal length of the mirror in water will be