List of top Physics Questions on Optics

A thin convex lens of focal length \( 5 \) cm and a thin concave lens of focal length \( 4 \) cm are combined together (without any gap), and this combination has magnification \( m_1 \) when an object is placed \( 10 \) cm before the convex lens.

Keeping the positions of the convex lens and the object undisturbed, a gap of \( 1 \) cm is introduced between the lenses by moving the concave lens away. This leads to a change in magnification of the total lens system to \( m_2 \).

The value of \( \dfrac{m_1}{m_2} \) is

The core of an optical fibre is surrounded by

For a prism of angle \(5^\circ\), the angle of minimum deviation \((\delta)\) varies with refractive index \((\mu)\) as shown in the graph. The slope of the graph is: center

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In Young’s double slit experiment, the ratio of intensities of maxima and minima is \(25:9\). The ratio of intensities of two slits is:

An object is placed at a distance of \(15\,\text{cm}\) from a convex lens of focal length \(10\,\text{cm}\). On the other side of the lens, at its focus, a convex mirror is placed such that final image formed coincides with the object. The focal length of convex mirror is:

A ray of light is incident normally on a refracting face of a prism. The subsequent journey of the ray through the prism is shown in the figure. The refractive index of the prism material is \(1.5\). Find the angle of the prism \((\angle A)\).

A double convex lens is made of a certain material. The refractive index of the material of the lens is \(1.55\) for violet rays and \(1.50\) for red rays. If the focal length of the lens is \(20\) cm for violet rays, then the focal length of the lens for red rays is

A rainbow is formed due to which of the following phenomena of light?

Interference fringes produced by a double slit arrangement using a monochromatic light of wave length 5,890Å have an angular fringe width \( 0.28^\circ \). If the entire arrangement is immersed in water, the new angular fringe width will be (\( ^a\mu_w = 4/3 \)):

A rectangular glass block of thickness 10 cm and refractive index 1.5 is placed over a small coin. A beaker is filled with water of refractive index 4/3 to a height of 10 cm and placed over the glass block. The apparent depth of coin when viewed at near normal incidence is:

Convex lens of focal length 20 cm and a concave lens of focal length of 30 cm are separated by a distance of 10 cm. Equivalent power of this arrangement is:

In a superconducting ring, a persistent current has been flowing without decay for years. This is possible because:

In Optical Fiber communication, the signal is transmitted in the form of:

A compound microscope consists of an objective lens of focal length \( f_{o}=1~\text{cm} \) and an eyepiece of focal length \( f_{e}=5~\text{cm} \). An object is placed 1.2 cm in front of the objective. The final image is formed at the least distance of distinct vision. The nature of the intermediate image and the total magnification of the microscope are:

How fast a person should drive his car so that the red signal of light appears green? (wavelengths of red and green colours are 6200 and 5400 respectively)

If a person cannot see objects closer than 100 cm, the power of lens required to read at 25 cm is:

If Young's double slit experiment is done in air first and then if the experiment is conducted by immersing the apparatus in water, the fringe width:

When a light ray incidents on an equilateral prism of material of refractive index $\sqrt{2}$, the angle of minimum deviation is D. If the light ray incidents on another equilateral prism of material of refractive index $\sqrt{3}$, then the angle of minimum deviation is:

For an astronomical telescope of length 126 cm in normal adjustment, if the focal length of the objective is 850 % more than that of its eyepiece, then the focal length of the eyepiece is:

A convex lens of refractive index \(1.5\) and focal length \(f=18\) cm is immersed in water. The difference in focal lengths of the given lens when it is in water and in air is \( \alpha \times f \). Find the value of \( \alpha \). (Given: refractive index of water \(=\dfrac{4}{3}\))

Given below are two statements: Statement I: A plane wave after passing through a prism remains a plane wave, but passing through a small pin hole may become a spherical wave. Statement II: The curvature of a spherical wave emerging from a slit will increase for increasing slit width. In the light of the above statements, choose the correct answer:

The magnitudes of power of a biconvex lens (refractive index \(1.5\)) and that of a plano-convex lens (refractive index \(1.7\)) are same. If the curvature of the plano-convex lens exactly matches with the curvature of the back surface of the biconvex lens, then the ratio of radii of curvature of the front and back surfaces of the biconvex lens is:

A compound microscope is designed with two symmetric biconvex lenses. The objective lens is cut vertically, creating two identical plano-convex lenses. One of them is used in place of original objective lens. To retain same magnification keeping the object distance unchanged, the tube length has to be:

A telescope with objective diameter \(R\) is used to observe a distant star emitting light of wavelength 500 nm, at a resolution of \(5 \times 10^{-7}\) radian. The value of \(R\) is ________ cm.

In a Young's double slit experiment, the intensity at a point where the path difference is $\frac{\lambda}{6}$ ($\lambda$ being the wavelength of the light used) is $I$. If $I_{0}$ denotes the maximum intensity, $\frac{I}{I_{0}}$ is