Assertion: The air bubble shines in water.

Reason: Air bubble in water shines due to the refraction of light.

Assertion: A convex mirror is used as a rearview mirror.

Reason: Convex mirror always forms a virtual, erect, and diminished image for real objects.

Minimum angular magnification produced by an astronomical telescope having a focal length of field lens and ocular 200 cm and 5 cm respectively is 

Assertion: When a convex glass lens is dipped in water, its focal length increases.

Reason: When the lens is dipped in water, its light-bending capacity increases.

The size of the image formed by a convex lens is one-fourth os the size of a real object. If the focal length of the lens is 30 cm, then the distance of the object from the lens is

Assertion: The number of images of an object held between two plane mirrors perpendicular to each other is 3.

Reason: Number of images = $\frac{360°}{\theta }$, where $\theta$ is the angle between the mirror in degree.

Which one of the following is correct regarding the scattering of light?

A concave lens forms the image of an object such that the distance between the object and image is 10 cm. If magnification of the image is $\frac{1}{4}$, the focal length of the lens is:

A point object O is placed at distance 20 cm from a biconvex lens of the radius of curvature 20 cm and $\mu$ = 1.5. The final image produced by lens and mirror combination will be at:

A small candle, 2.5 cm in size is placed at 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image?

A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. What is magnification?

A small bulb is placed at the bottom of a tank containing water to a depth of 80 cm. What is the area of the surface of water through which light from the bulb can emerge out? The Refractive index of water is 1.33. (Consider the bulb to be a point source.)

A prism is made of glass of unknown refractive index. A parallel beam of light is incident on the face of the prism. The angle of minimum deviation is measured to be 40°. What is the refractive index of the material of the prism? The refracting angle of the prism is 60°. 

Double-convex lenses are to be manufactured from a glass of refractive index 1.55 with both faces of the same radius of curvature. What is the radius of curvature required if the focal length is to be 20 cm?

Monochromatic light of wavelength 589 nm is incident from the air on a water surface. What is the wavelength of reflected light? The refractive index of water is 1.33.

The refractive index of glass is 1.5. What is the speed of light in glass? 

$$\begin{gathered} \left(1\right) 2\times {10}^8 m/s \\ \left(2\right) 3\times {10}^8 m/s \\ \left(3\right) 1.5\times {10}^8 m/s \\ \left(4\right) 2.2\times {10}^8 m/s \end{gathered}$$

Light of wavelength 5000 Å falls on a plane reflecting surface. For what angle of incidence is the reflected ray normal to the incident ray?

A tank is filled with water to a height of 12.5 cm. The apparent depth of a needle lying at the bottom of the tank is measured by a microscope to be 9.4 cm.  If water is replaced by a liquid of refractive index 1.63 up to the same height, by what distance would the microscope have to be moved to focus on the needle again?

A beam of light converges at a point P. Now a lens is placed in the path of the convergent beam 12cm from P. At what point does the beam converge if the lens is a convex lens of focal length 20cm?

 A compound microscope consists of an objective lens of focal length 2.0 cm and an eyepiece of focal length 6.25 cm separated by a distance of 15 cm. How far from the objective should an object be placed in order to obtain the final image at the least distance of distinct vision (25 cm)?

A person with a normal near point (25 cm) using a compound microscope with an objective of focal length 8.0 mm and an eyepiece of focal length 2.5 cm can bring an object placed at 9.0 mm from the objective in sharp focus. What is the separation between the two lenses?

A small telescope has an objective lens of a focal length 144 cm and an eyepiece of focal length 6.0 cm. What is the magnifying power of the telescope?

A giant refracting telescope at an observatory has an objective lens of focal length 15 m. If an eyepiece of focal length 1.0 cm is used, what is the angular magnification of the telescope?

A small pin fixed on a tabletop is viewed from above from a distance of 50 cm. By what distance would the pin appear to be raised if it is viewed from the same point through a 15 cm thick glass slab held parallel to the table? (The Refractive index of glass is 1.5)

A cross-section of a ‘light pipe’ made of a glass fiber of refractive index 1.68. The outer covering of the pipe is made of a material of refractive index 1.44. What is the range of the angles of the incident rays with the axis of the pipe for which total reflections inside the pipe take place, as shown in the figure?

$$\begin{gathered} \left(1\right) 0^0<i<{45}^0 \\ \left(2\right) 0^0<i<{60}^0 \\ \left(3\right) {45}^0<i<{75}^0 \\ \left(4\right) {45}^0<i<{90}^0 \end{gathered}$$

The image of a small electric bulb fixed on the wall of a room is to be obtained on the opposite wall 3 m away by means of a large convex lens. What is the maximum possible focal length of the lens required for the purpose?

A screen is placed 90 cm from an object. The image of the object on the screen is formed by a convex lens at two different locations separated by 20 cm. The focal length of the lens is:

At what angle should a ray of light be incident on the face of a prism of refracting angle 60° so that it just suffers total internal reflection at the other face? The refractive index of the material of the prism is 1.524.

$$\begin{gathered} \left(1\right) 29.{75}^0 \\ \left(2\right) {19}^0 \\ \left(3\right) 17.{23}^0 \\ \left(4\right) 19.{57}^0 \end{gathered}$$

A man with normal near point (25 cm) reads a book with small print using a magnifying glass: a thin convex lens of focal length 5 cm. What is the closest distance at which he should keep the lens from the page so that he can read the book when viewing through the magnifying glass?

A man with normal near point (25 cm) reads a book with small print using a magnifying glass: a thin convex lens of focal length 5 cm. What is the ratio of maximum and the minimum angular magnification (magnifying power) possible using the above simple microscope?

$$\begin{gathered} \left(1\right) \frac{6}{5} \\ \left(2\right) \frac{5}{6} \\ \left(3\right) \frac{3}{2} \\ \left(4\right) \frac{2}{3} \end{gathered}$$