List of top Physics Questions

In Bohr's atomic model, the electron is assumed to revolve in a circular orbit of radius 0.5 Å. If the speed of the electron is $2.2 \times 10^6$ m/s, then the current associated with the electron will be _________ $\times 10^{-2}$ mA. [Take $\pi$ as 22/7]
In a uniform magnetic field, the magnetic needle has a magnetic moment $9.85 \times 10^{-2}$ A/m$^2$ and moment of inertia $5 \times 10^{-6}$ kg m$^2$. If it performs 10 complete oscillations in 5 seconds then the magnitude of the magnetic field is _________ mT. [Take $\pi^2$ as 9.85]
A stone of mass 20 g is projected from a rubber catapult of length 0.1 m and area of cross section $10^{-6}$ m$^2$ stretched by an amount 0.04 m. The velocity of the projected stone is _________ m/s. (Young's modulus of rubber = $0.5 \times 10^9$ N/m$^2$)
Assertion A : If in five complete rotations of the circular scale, the distance travelled on main scale is 5 mm and there are 50 total divisions on circular scale, then least count is 0.001 cm.
Reason R : Least Count = $\frac{\text{Pitch}}{\text{Total divisions on circular scale}}$
A ball is thrown up with a certain velocity so that it reaches a height 'h'. Find the ratio of the two different times of the ball reaching $\frac{h}{3}$ in both the directions.
A particle starts executing simple harmonic motion (SHM) of amplitude 'a' and total energy E. At any instant, its kinetic energy is $\frac{3E}{4}$ then its displacement 'y' is given by :
A body takes 4 min. to cool from 61$^\circ$C to 59$^\circ$C. If the temperature of the surroundings is 30$^\circ$C, the time taken by the body to cool from 51$^\circ$C to 49$^\circ$C is :
Two identical tennis balls each having mass 'm' and charge 'q' are suspended from a fixed point by threads of length 'l'. What is the equilibrium separation when each thread makes a small angle '$\theta$' with the vertical ?
The number of molecules in one litre of an ideal gas at 300 K and 2 atmospheric pressure with mean kinetic energy $2 \times 10^{-9}$ J per molecule is :
A 0.07 H inductor and a 12 $\Omega$ resistor are connected in series to a 220 V, 50 Hz ac source. The approximate current in the circuit and the phase angle between current and source voltage are respectively. [Take $\pi$ as 22/7]
Two capacitors of capacities 2C and C are joined in parallel and charged up to potential V. The battery is removed and the capacitor of capacity C is filled completely with a medium of dielectric constant K. The potential difference across the capacitors will now be :
The relative permittivity of distilled water is 81. The velocity of light in it will be : (Given $\mu_r = 1$)
If 'f' denotes the ratio of the number of nuclei decayed Nd to the number of nuclei at t=0 N0 then for a collection of radioactive nuclei, the rate of change of 'f' with respect to time is given as: [$\lambda$ is the radioactive decay constant]
In Young's double slit experiment, if the source of light changes from orange to blue then:
A cylindrical tube, with its base as shown in the figure, is filled with water It is moving down with a constant acceleration $a$ along a fixed inclined plane with angle $\theta=45^{\circ} P_{1}$ and $P_{2}$ are pressures at points $1$ and $2$, respectively located at the base of the tube. Let $\beta=\left(P_{1}-P_{2}\right) /(\rho g d)$, where $\rho$ is density of water, $d$ is the inner diameter of the tube and $g$ is the acceleration due to gravity. Which of the following statement(s) is(are) correct?
A cylindrical tube, with its base as shown in the figure, is filled with water. It is moving down with a
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 ?
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:
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 ?

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. 

 

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

 

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 :

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 \( \sqrt{5} = 2.3 \)) 

A sphere of radius 'a' and mass 'm' rolls along a horizontal plane with constant speed $v_0$. It encounters an inclined plane at angle $\theta$ and climbs upward. Assuming that it rolls without slipping, how far up the sphere will travel? 

 

A current of 6 A enters one corner P of an equilateral triangle PQR having 3 wires of resistance 2 $\Omega$ each and leaves by the corner R. The currents $i_1$ in ampere is ________ . 

The percentage increase in the speed of transverse waves produced in a stretched string if the tension is increased by 4 percent , will be ________ .