Free CBSE - Class 12 Physics - Ray Optics and Optical Instruments worksheets

A Cassegrain telescope uses two mirrors. Such a telescope is built with the mirrors ((20))mm apart. If the radius of curvature of the large mirror is ((220))mm and the small mirror is ((140))mm, where will the final image of an object at infinity be?

Light incident normally on a plane mirror attached to a galvanometer coil retraces backwards as shown in Fig. 9.29. A current in the coil produces a deflection of ((3.5^{\circ})) of the mirror. What is the displacement of the reflected spot of light on a screen placed ((1.5)) m away?

Figure 9.30 shows an equiconvex lens (of refractive index ((1.50))) in contact with a liquid layer on top of a plane mirror. A small needle with its tip on the principal axis is moved along the axis until its inverted image is found at the position of the needle. The distance of the needle from the lens is measured to be ((45.0))cm. The liquid is removed and the experiment is repeated. The new distance is measured to be ((30.0))cm. What is the refractive index of the liquid?