List of top Physics Questions

Power of point source is 450 watts. Radiation pressure on a perfectly reflecting surface at a distance of 2 meters is:

In a Young's double slit experiment, the slits are separated by 0.2 mm. If the slits separation is increased to 0.4 mm, the percentage change of the fringe width is:

Width of one of the two slits in a Young's double slit interference experiment is half of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern is :

A tube of length 1m is filled completely with an ideal liquid of mass 2M, and closed at both ends. The tube is rotated uniformly in horizontal plane about one of its ends. If the force exerted by the liquid at the other end is $ F $ and the angular velocity of the tube is $ \omega $, then the value of $ \alpha $ is ______ in SI units.

The center of mass of a thin rectangular plate (fig - x) with sides of length $ a $ and $ b $, whose mass per unit area ($ \sigma $) varies as $ \sigma = \sigma_0 \frac{x}{ab} $ (where $ \sigma_0 $ is a constant), would be

The moment of inertia of a uniform rod of mass $ m $ and length $ l $ is $ \alpha $ when rotated about an axis passing through the centre and perpendicular to the length. If the rod is broken into equal halves and arranged as shown, then the moment of inertia about the given axis is:

The temperature of a body in air falls from $ 40^\circ \text{C} $ to $ 24^\circ \text{C} $ in 4 minutes. The temperature of the air is $ 16^\circ \text{C} $. The temperature of the body in the next 4 minutes will be:

A circular disk of radius $ R $ meter and mass $ M $ kg is rotating around the axis perpendicular to the disk. An external torque is applied to the disk such that $ \theta(t) = 5t^2 - 8t $, where $ \theta(t) $ is the angular position of the rotating disk as a function of time $ t $. How much power is delivered by the applied torque, when $ t = 2 $ s?

A solid sphere of mass $ m $ and radius $ r $ is allowed to roll without slipping from the highest point of an inclined plane of length $ L $ and makes an angle of $ 30^\circ $ with the horizontal. The speed of the particle at the bottom of the plane is $ v_1 $. If the angle of inclination is increased to $ 45^\circ $ while keeping $ L $ constant, the new speed of the sphere at the bottom of the plane is $ v_2 $. The ratio of $ v_1^2 : v_2^2 $ is:

Two iron solid discs of negligible thickness have radii $ R_1 $ and $ R_2 $ and moment of inertia $ I_1 $ and $ I_2 $, respectively. For $ R_2 = 2R_1 $, the ratio of $ I_1 $ and $ I_2 $ would be $ \frac{1}{x} $, where $ x $ is:

A disc is performing pure rolling if the speed of the top point is 8 m/s. Find the speed of point B.

The moment of inertia of a solid disc rotating along its diameter is 2.5 times higher than the moment of inertia of a ring rotating in a similar way. The moment of inertia of a solid sphere which has the same radius as the disc and rotating in similar way, is $ n $ times higher than the moment of inertia of the given ring. Here, $ n = $:

A rod of linear mass density $ \lambda $ and length $ L $ is bent to form a ring of radius $ R $. Moment of inertia of the ring about any of its diameter is:

A force of 49 N acts tangentially at the highest point of a sphere (solid) of mass 20 kg, kept on a rough horizontal plane. If the sphere rolls without slipping, then the acceleration of the center of the sphere is

Moment of inertia of a rod of mass $ M $ and length $ L $ about an axis passing through its center and normal to its length is $ \alpha $. Now the rod is cut into two equal parts and these parts are joined symmetrically to form a cross shape. Moment of inertia of cross about an axis passing through its center and normal to the plane containing cross is:

A circular ring and a solid sphere having same radius roll down on an inclined plane from rest without slipping. The ratio of their velocities when reached at the bottom of the plane is $\sqrt{\frac{\mathrm{x}}{5}}$ where $\mathrm{x}=$ _______.

A solid sphere with uniform density and radius $ R $ is rotating initially with constant angular velocity ($ \omega_1 $) about its diameter. After some time during the rotation, it starts losing mass at a uniform rate, with no change in its shape. The angular velocity of the sphere when its radius becomes $ \frac{R}{2} $ is $ \omega_2 $. The value of $ x $ is ________.

M and R be the mass and radius of a disc. A small disc of radius R/3 is removed from the bigger disc as shown in figure. The moment of inertia of remaining part of bigger disc about an axis AB passing through the centre O and perpendicular to the plane of disc is $ \frac{4}{x} MR^2 $. The value of x is ____.

A thin solid disk of 1 kg is rotating along its diameter axis at the speed of 1800 rpm. By applying an external torque of $25\pi$ Nm for 40s, the speed increases to 2100 rpm. The diameter of the disk is ______ m.

A cord of negligible mass is wound around the rim of a wheel supported by spokes with negligible mass. The mass of the wheel is 10 kg and radius is 10 cm and it can freely rotate without any friction. Initially the wheel is at rest. If a steady pull of 20 N is applied on the cord, the angular velocity of the wheel, after the cord is unwound by 1 m, will be:

Which of the following are correct expression for torque acting on a body?
A. $\ddot{\tau}=\ddot{\mathrm{r}} \times \ddot{\mathrm{L}}$
B. $\ddot{\tau}=\frac{\mathrm{d}}{\mathrm{dt}}(\ddot{\mathrm{r}} \times \ddot{\mathrm{p}})$
C. $\ddot{\tau}=\ddot{\mathrm{r}} \times \frac{\mathrm{d} \dot{\mathrm{p}}}{\mathrm{dt}}$
D. $\ddot{\tau}=\mathrm{I} \dot{\alpha}$
E. $\ddot{\tau}=\ddot{\mathrm{r}} \times \ddot{\mathrm{F}}$
( $\ddot{r}=$ position vector; $\dot{\mathrm{p}}=$ linear momentum; $\ddot{\mathrm{L}}=$ angular momentum; $\ddot{\alpha}=$ angular acceleration; $\mathrm{I}=$ moment of inertia; $\ddot{\mathrm{F}}=$ force; $\mathrm{t}=$ time $)$
Choose the correct answer from the options given below:

If $\overrightarrow{\mathrm{L}}$ and $\overrightarrow{\mathrm{P}}$ represent the angular momentum and linear momentum respectively of a particle of mass ' $m$ ' having position vector $\overrightarrow{\mathrm{r}}=\mathrm{a}(\hat{\mathrm{i}} \cos \omega \mathrm{t}+\hat{\mathrm{j}} \sin \omega \mathrm{t})$. The direction of force is

Three infinitely long wires with linear charge density $ \lambda $ are placed along the x-axis, y-axis and z-axis respectively. Which of the following denotes an equipotential surface?

Two capacitors $ C_1 $ and $ C_2 $ are connected in parallel to a battery. Charge-time graph is shown below for the two capacitors. The energy stored with them are $ U_1 $ and $ U_2 $, respectively. Which of the given statements is true?

Arrange the following in the ascending order of wavelength ($ \lambda $):
(A) Microwaves ($ \lambda_1 $)
(B) Ultraviolet rays ($ \lambda_2 $)
(C) Infrared rays ($ \lambda_3 $)
(D) X-rays ($ \lambda_4 $) \text{Choose the most appropriate answer from the options given below:}