A ray of monochromatic light is passing through an equilateral prism $(A B C)$ as shown in the figure. The refracted ray $(Q R)$ is parallel to its base $(B C)$ and the angle of incidence $(i)$ is $50^{\circ}$. Then the angle of deviation $(\delta)$ is:

In a concave lens, a ray of light emanating from the object parallel to the principal axis of the lens after refraction:

A microscope has an objective of focal length 2 cm , eyepiece of focal length 4 cm and the tube length of 40 cm . If the distance of distinct vision of eye is 25 cm , the magnification in the microscope is

In a certain camera, a combination of four similar thin convex lenses are arranged axially in contact. Then the power of the combination and the total magnification in comparison to the power ( $p$ ) and magnification ( $m$ ) for each lens will be, respectively