Geometrical Optics

A microscope is focused on an object at the bottom of a bucket. If liquid with refractive index $\frac{5}{3}$ is poured inside the bucket, then the microscope has to be raised by $30 \mathrm{~cm}$ to focus the object again. The height of the liquid in the bucket is :

A microscope was initially placed in air (refractive index 1). It is then immersed in oil (refractive index 2). For a light whose wavelength in air is $\lambda$, calculate the change of microscope's resolving power due to oil and choose the correct option.

In normal adujstment, for a refracting telescope, the distance between objective and eye piece is $30 \mathrm{~cm}$. The focal length of the objective, when the angular magnification of the telescope is 2 , will be :

A scientist is observing a bacteria through a compound microscope. For better analysis and to improve its resolving power he should. (Select the best option)

In a reflecting telescope, a secondary mirror is used to:

Identify the physical quantity that cannot be measured using spherometer :

If two mirrors are kept at ${60^ \circ }$ to each other, then the number of images formed by them is

To get three images of a single object, one should have two plane mirrors at an angle of

A car is fitted with a convex side-view mirror of focal length $20$ $cm$. A second car $2.8m$ behind the first car is overtaking the first car at a relative speed of $15$ $m/s$. The speed of the image of the second car as seen in the mirror of the first one is :

Two plane mirrors are inclined to each other such that a ray of light incident on the first mirror (M₁) and parallel to the second mirror (M₂) is finally reflected from the second mirror (M₂) parallel to the first mirror (M₁). The angle between the two mirrors will be :