List of top Physics Questions

When a proton is released from rest in a room, it starts with an initial acceleration $a_0$ towards west. When it is projected towards north with a speed $v_0$ it moves with an initial acceleration $3a_0$ towards west. The electric and magnetic fields in the room are:

Infinite number of bodies, each of mass 2 kg are situated on x-axis at distance 1m, 2m, 4m, 8m, ...., respectively, from the origin. The resulting gravitational potential due to this system at the origin will be

An explosion breaks a rock into three parts in a horizontal plane. Two of them go off at right angles to each other. The first part of mass $1\, kg$ moves with a speed of $12 \, ms^{-1}$ and the second part of mass $2 \,kg$ moves with $8 \, ms^{-1}$ speed. If the third part files off with $4 \, ms^{-1}$ speed, then its mass is :

The heart is pumping blood at x kg per unit time, with a constant velocity v. The force required is

The transverse displacement of a string fixed at both ends is given by $y=0.6 \sin \left(\frac{2 \pi x}{3}\right) \cos (120 \pi t)$ where $x$ and $y$ are in metres and $t$ is in seconds. The length of the string is $1.5\, m$ and its mass is $3.0 \times 10^{-2} kg$. The tension in the string is equal to

A $200\, W$ sodium street lamp emits yellow light of wavelength $0.6 \, \mu m. $ Assuming it to be $25 \% $ efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is

A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It.

A magnetic needle suspended parallel to a magnetic field requires $\sqrt 3 \,J$ of work to turn it through $60^\circ.$ The torque needed to maintain the needle in this position will be

An $\alpha -$ particle moves in a circular path of radius $0.83\, cm$ in the presence of a magnetic field of $0.25\, Wb/m^2. $ The de Broglie wavelength associated with the particle will be (Take $h = 6.63 ? 10^{-34} J\, s$, $e =1.6 ?10^{-19}C$)

$C$ and $Si$ both have same lattice structure; having $4$ bonding electrons in each. However, $C$ is insulator where as $Si$ is intrinsic semiconductor. This is because

If the momentum of an electron is changed by P, then the de Broglie wavelength associated with it changes by $0.5 \%. $ The initial momentum of electron will be

A slab of stone of area 0.36 m2 and thickness 0.1 m is exposed on the lower surface to steam at 100$^{\circ}$C. A block of ice at 0$^{\circ}$C rests on the upper surface of the slab. In one hour 4.8 kg of ice is melted. The thermal conductivity of slab is (Given latent heat of fusion of ice = $ 3.36 \times 10^5 J kg^{-1})$

The equation of a simple harmonic wave is given by $y=3 \sin \frac{\pi}{2}(50t-x), $ where $x$ and $y$ are in metres and $t$ is in seconds. The ratio of maximum particle velocity to the wave velocity is

The transverse displacement \( y(x, t) \) of a wave on a string is given by \( y(x,t) = e^{-(x^2 + t^2)} \sin(kx - \omega t) \). This represents a:

What is the flux through a cube of side a if a point charge of q is at one of its corner?

A mixture consists of two radioactive materials $ A_1$ and $A_2$ with half lives of $20\,s$ and $10\, s$ respectively. Initially the mixture has $40 \,g$ of $A_1$ and $160 \,g$ of $A_2$ The amount of the two in the mixture will become equal after

The potential energy of a particle in a force field is $ U=\frac{A}{r^2}-\frac{B}{r}$ where A and B are positive constants and r is the distance of particle from the centre of the field. For stable equilibrium, the distance of the particle is

If voltage across a bulb rated $220 \,V$- $100\, W$ drops by $2.5\%$ of its rated value, the percentage of the rated value by which the power would decrease is

In the circuit shown the cells A and B have negligible resistances. For $V_A =12\, V,\, R_1 =500\, \Omega $ and $ R =100\, \Omega $ the galvanometer (G) shows no deflection. The value of $V_B$ is

A large drop of oil (density $0.8 \,g / cm ^{3}$ and viscosity $\eta_{0}$ ) floats up through a column of another liquid (density $1.2\, g / cm ^{3}$ and viscosity $\eta_{L}$ ). Assuming that the two liquids do not mix, the velocity with which the oil drop rises will depend on :

"Plum pudding" model of an atom was proposed by

A glass hemisphere of radius 0.1 cm and refractive index 1.5 is placed over a spot on a table and the spot is viewed from above. The spot appears to be

If $x =at + bt^2$ where $x$ is measured in m and t ins, thenthe dimension of (b/a) is

A block of mass 0.1 kg is held against a wall by applying a horizontal force of 5 N on it. If $\mu,$ between the wall? and the block is 0.5, the magnitude of the frictional force acting on the block is

A particle is moving eastward with velocity $5 \, m \, s^{-1}$ In 10 s the velocity changes to $5\, m\, s^{-1}$ northwards. The average acceleration in this time is