List of top Physics Questions

Radioactive decay will occur as follows:
\(_{86}^{220}Rn→_{84}^{216}Po+_2^4He\); Half life = 55s
\(_{84}^{216}Po→_{82}^{216}Pb+_2^4He\); Half life = 0.66s
\(_{82}^{812}Pb→_{82}{212}BL+λ^oe\); Half life = 10.6 h
If a certain mass of radon (Rn=220) is allowed to decay in a certain container; then after 5 minutes the element with the greater mass will be

A body is projected vertically upwards. The times corresponding to height h while ascending and while descending are \(t_1\) and \(t_2\), respectively. Then, the velocity of projection will be
(take g as acceleration due to gravity)

A rocket is intended to leave the Earth's gravitational field. The fuel in tis main engine is a little less than the amount that is necessary and an auxiliary engine, (only capable of operating for a short time) has to be used as well. When is it best to switch on the auxiliary engine?

A particle of mass \(m\) is executing oscillation about the origin on X-axis. Its potential energy is \(V(x) = K|x|^3\). Where \(K\) is a positive constant. If the amplitude of oscillation is \(a\), then its time period \(T\) is proportional to

A cylindrical tube of uniform cross-sectional area \(A\) is filled with two air tight frictionless pistons. The pistons are connected to each other by a metallic wire. Initially, the pressure of the gas is \(p_o\) and temperature is \(T_o\), atmospheric pressure is also \(p_o\). Now, the temperature of the gas is increased to \(2T_o\), the tension of wire will be

A long straight wire is carrying current \(I\) in +z direction. The x-y plane contains a closed circular loop carrying current \(I_2\) and not encircling the straight wire. The force on the loop will be

The turns of a solenoid, designed to provide a given magnetic flux density along its axis, are wound to fill the space between two concentric cylinders of fixed radii. How should the diameter d of the wire used be chosen so as to minimize the heat dissipated in the windings?

Two 20 g flatworms climb over a very thin wall, 10 cm high. One of the worm is 20 cm long, the other is wider and only 10 cm long. Which of the following statement is correct regarding them?

A thin prism having refracting angle $10^{\circ}$ is made of glass of refractive index $1.42$. This prism is combined with another thin prism of glass of refractive index $1.7$. This combination produces dispersion without deviation. The refracting angle of second prism should be :

If kinetic energy of a body is increased by $300$ % then percentage change in momentum will be

The kinetic energy of electron and photon arc the same. The relation between their De - Broglie wavelengths $ \lambda _e $ and $ \lambda _p $ is

A solid cylinder of mass $ M $ and radius $ R $ rolls on a flat surface. Find its moment of inertia about the line of contact.

An extrinsic semiconductor with electrons as majority carriers can be obtained by doping $ Ge $ or $ Si $ with

The difference between the maximum and minimum values of resistance of a resistor with the color scheme green-green-red-silver is

Which of the following is the indirect way of generating $ FM $ ?

A physical quantity X is given by $X=\frac{2k^{3}l^{2}}{m\sqrt{n}}$ The percentage error in the measurements of k, l, m and n are 1%, 2%, 3% and 4% respectively. The value of X is uncertain by

The magnetic field due to a current in a straight wire segment of length $L$ at a point on its perpendicular bisector at a distance $r (r >> L)$

A metal rod of length ????and cross-sectional area ????is heated through $???? \, {^{\circ}C}$. What is the force required to prevent the expansion of the rod lengthwise ? [Y = Young's modulus of the material of rod , $\alpha$ = coefficient of linear expansion]

A lift of mass $m$ is connected to a rope which is moving upward with maximum acceleration $a$. For maximum safe stress, the elastic limit of the rope, is $T$. The minimum diameter of the rope is (g = gravitational acceleration)

The resistance of a wire is ‘R’ ohm. If it is melted and stretched to ‘n’ times its original length, its new resistance will be

A thin prism having refracting angle 10° is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be

The two nearest harmonics of a tube closed at one end and open at other end are 220 Hz and 260 Hz. What is the fundamental frequency of the system?

A rope is wound around a hollow cylinder of mass 3 kg and radius 40 cm. What is the angular acceleration of the cylinder if the rope is pulled with a force of 30 N?

A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle θ, the spot of the light is found to move through a distance y on the scale. The angle θ is given by

Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time t₁. On other days, if she remains stationary on the moving escalator, then the escalator takes her up in time t₂. The time taken by her to walk up on the moving escalator will be