List of top Physics Questions

A coil in the shape of an equilateral triangle of side 10 cm lies in a vertical plane between the pole pieces of permanent magnet producing a horizontal magnetic field 20 mT. The torque acting on the coil when a current of 0.2 A is passed through it and its plane becomes parallel to the magnetic field will be $ \sqrt{x} \times 10^{-5} $ Nm. The value of x is __________.

The fractional change in the magnetic field intensity at a distance 'r' from centre on the axis of current carrying coil of radius 'a' to the magnetic field intensity at the centre of the same coil is : (Take $r \ll a$)

A proton, a deuteron and an $\alpha$ particle are moving with same momentum in a uniform magnetic field. The ratio of magnetic forces acting on them is __________ and their speed is __________, in the ratio.

A proton and an $\alpha$-particle enter into a magnetic field at right angles. The ratio of the radii of trajectory of proton to that of $\alpha$-particle is 2 : 1. The ratio of $K_p : K_{\alpha}$ is:

An object is placed at the focus of concave lens having focal length f. What is the magnification and distance of the image from the optical centre of the lens ?

Cross-section view of a prism is the equilateral triangle ABC shown in the figure. The minimum deviation is observed using this prism when the angle of incidence is equal to the prism angle. The time taken by light to travel from P (midpoint of BC) to A is ________ $\times 10^{-10}$ s. (Given, speed of light in vacuum $= 3 \times 10^8$ m/s and $\cos 30^\circ = \frac{\sqrt{3}}{2}$)
\begin{center} \includegraphics[width=0.3\textwidth]{prism_diagram} \end{center}

In a Young's double slit experiment, the slits are separated by 0.3 mm and the screen is 1.5 m away from the plane of slits. Distance between fourth bright fringes on both sides of central bright fringe is 2.4 cm. The frequency of light used is ________ $\times 10^{14}$ Hz.

Two plane mirrors $ M_1 $ and $ M_2 $ are at right angle to each other shown. A point source 'P' is placed at 'a' and '2a' meter away from $ M_1 $ and $ M_2 $ respectively. The shortest distance between the images thus formed is : (Take $ \sqrt{5} = 2.3 $)

The light waves from two coherent sources have same intensity $I_1 = I_2 = I_0$. In interference pattern the intensity of light at minima is zero. What will be the intensity of light at maxima ?

An object is placed beyond the centre of curvature C of the given concave mirror. If the distance of the object is $d_1$ from C and the distance of the image formed is $d_2$ from C, the radius of curvature of this mirror is :

An object is placed at a distance of 12 cm from a convex lens. A convex mirror of focal length 15 cm is placed on other side of lens at 8 cm as shown in the figure. Image of object coincides with the object. When the convex mirror is removed, a real and inverted image is formed at a position. The distance of the image from the object will be __________ (cm).

Find the distance of the image from object O, formed by the combination of lenses in the figure :

A source of light is placed in front of a screen. Intensity of light on the screen is I. Two Polaroids P$_1$ and P$_2$ are so placed in between the source of light and screen that the intensity of light on screen is I/2. P$_2$ should be rotated by an angle of __________ (degrees) so that the intensity of light on the screen becomes $\frac{3I}{8}$.

White light is passed through a double slit and interference is observed on a screen 1.5 m away. The separation between the slits is 0.3 mm. The first violet and red fringes are formed 2.0 mm and 3.5 mm away from the central white fringes. The difference in wavelengths of red and violet light is _________ nm.

Curved surfaces of a plano-convex lens of refractive index $\mu_1$ and a plano-concave lens of refractive index $\mu_2$ have equal radius of curvature as shown in figure. Find the ratio of radius of curvature to the focal length of the combined lenses.

Two coherent light sources having intensity in the ratio $2x$ produce an interference pattern. The ratio $(I_{max} - I_{min}) / (I_{max} + I_{min})$ will be :

In a YDSE, width of one slit is three times the other. Amplitude is proportional to slit-width. Find the ratio $I_{max}/I_{min}$.

Consider the diffraction pattern obtained from the sunlight incident on a pinhole of diameter 0.1 $\mu$m. If the diameter of the pinhole is slightly increased, it will affect the diffraction pattern such that:

An unpolarized light beam is incident on the polarizer of a polarization experiment and the intensity of light beam emerging from the analyzer is measured as 100 Lumens. Now, if the analyzer is rotated around the horizontal axis (direction of light) by 30° in clockwise direction, the intensity of emerging light will be ________ Lumens.

A galaxy is moving away from the earth at a speed of 286 kms$^{-1}$. The shift in the wavelength of a redline at 630 nm is x $\times 10^{-10}$ m. The value of x, to the nearest integer, is ________. [Take the value of speed of light c, as 3 $\times 10^8$ ms$^{-1}$]

In the Young's double slit experiment, the distance between the slits varies in time as $d(t) = d_0 + a_0 \sin \omega t$; where $d_0, \omega$ and $a_0$ are constants. The difference between the largest fringe width and the smallest fringe width obtained over time is given as :

If the source of light used in a Young's double slit experiment is changed from red to violet :

A prism of refractive index $n_1$ and another prism of refractive index $n_2$ are stuck together (as shown in the figure). $n_1$ and $n_2$ depend on $\lambda$, the wavelength of light, according to the relation $n_1 = 1.2 + \frac{10.8 \times 10^{-14}}{\lambda^2}$ and $n_2 = 1.45 + \frac{1.8 \times 10^{-14}}{\lambda^2}$. The wavelength for which rays incident at any angle on the interface BC pass through without bending at that interface will be _________ nm.

The difference in the number of waves when yellow light propagates through air and vacuum columns of the same thickness is one. The thickness of the air column is ________ mm.
[Refractive index of air = 1.0003, wavelength of yellow light in vacuum = 6000 Å]

In Young's double slit arrangement, slits are separated by a gap of 0.5 mm, and the screen is placed at a distance of 0.5 m from them. The distance between the first and the third bright fringe formed when the slits are illuminated by a monochromatic light of 5890 Å is :