Calculate the focal length of given lens if the magnification is $-$0 5.

Assertion A convex mirror always make a virtual image.

Reason The ray always diverge after reflection from the convex mirror.

A lens of refractive index $\mu$ is put in a liquid of refractive index $\mu^{\prime}$. If the focal length of lens in air is $f$, then its focal length in liquid will be

In the given figure, the angle of reflection is

A thin prism $P_1$ of angle $4^{\circ}$ and refractive index 1.54 is combined with another prism $P_2$ of refractive index 1.72 produce dispersion without deviation, the angle of $P_2$ is

A simple telescope, consisting of an objective of focal length $60 \mathrm{~cm}$ and a single eye lens of focal length $5 \mathrm{~cm}$ is focused on a distant object in such a way that parallel rays emerge from the eye lens. If the object subtends an angle of $2^{\circ}$ at the objective, the angular width of the image is

Assertion : The mirror used in search lights are parabolic and not concave spherical.

Reason : In concave spherical mirror, the image formed is always virtual.

Assertion : Angle of deviation depends on the angle of prism.

Reason : For thin prism $\delta=(\mu-1) A$

Where $\delta=$ angle of deviation, $\mu=$ refractive index, $A=$ angle of prism