List of top Physics Questions

A pendulum made of a uniform wire of cross sectional area $A$ has time period $T$. When an additional mass $M$ is added to its bob, the time period changes to $T_M$. If the Young's modulus of the material of the wire is $Y$ then $\frac{1}{Y}$ is equal to ( $g =$ gravitational acceleration)

A simple harmonic oscillator of angular frequency $2 \,rad \,s^{-1}$ is acted upon by an external force $F= \sin\, t \,N$. If the oscillator is at rest in its equilibrium position at $t\, =\, 0$, its position at later times is proportional to :

A ball is projected up at an angle $\theta$ with horizontal from the top of a tower with speed $v$. It hits the ground at point $A$ after time $t_{A}$ with speed $v_{A}$ . Now, this ball is projected at same angle and speed from the base of the tower (located at point $P$) and it hits ground at point $B$ after time $t_{B}$ with speed $v_{B}$. Then

Two stones are thrown up simultaneously from the edge of a cliff $240\, m$ high with initial speed of $10\, m/s$ and $40\, m/s$ respectively. Which of the following graph best represents the time variation of relative position of the second stone with respect to the first? (Assume stones do not rebound after hitting the ground and neglect air resistance, take $g=10\, m/s^2$)

A thin convex lens of focal length ' $f'$ is put on a plane mirror as shown in the figure. When an object is kept at a distance ' $a$ ' from the lens-mirror combination, its image is formed at a distance $\frac{a}{3}$ in front of the combination. The value of ' $a$ ' is

You are asked to design a shaving mirror assuming that a person keeps it $10\,cm$ from his face and views the magnified image of the face at the closest comfortable distance of $25\, cm$. The radius of curvature of the mirror would then be :

In an ideal gas at temperature $T$, the average force that a molecule applies on the walls of a closed container depends on $T$ as $T^q$. A good estimate for $q$ is :

For plane electromagnetic waves propagating in the $z$ direction, which one of the following combination gives the correct possible direction for $\vec{E}$ and $\vec{B}$ field respectively ?

A train is moving on a straight track with speed $20\, ms^{-1}.$ It is blowing its whistle at the frequency of $1000\, Hz$. The percentage change in the frequency heard by a person standing near the track as the train passes him is close to (speed of sound $= 320\,ms^{-1}$)

A uniform solid cylindrical roller of mass '$m$' is being pulled on a horizontal surface with force $F$ parallel to the surface and applied at its centre. If the acceleration of the cylinder is '$a$' and it is rolling without slipping then the value of '$F$' is :

When current in a coil changes from $5 \,A$ to $2 \,A$ in $0.1\, s$, an average voltage of $50\, V$ is produced. The self - inductance of the coil is :

In the given circuit, charge $Q_2 $ on the $2 \mu F $ capacitor changes as $C$ is varied from $1 \mu F $ to $3 \mu F. $ $Q_2 $ as a function of $'C'$ is given properly by (figures are drawn schematically and are not to scale)

A uniformly charged solid sphere of radius $R$ has potential $V _{0}\, 9$ measured with respect to $\infty$ ) on its surface. For this sphere the equipotential surfaces with potentials $\frac{3 V _{0}}{2}$, $\frac{5 V _{0}}{4}, \frac{3 V _{0}}{4}$ and $\frac{ V _{0}}{4}$ have radius $R _{1}, R _{2}, R _{3}$ and $R _{4}$ respectively. Then

In the electric network shown, when no current flows through the $4\, \Omega$ resistor in the arm $EB$, the potential difference between the points $A$ and $D$ will be :

When $5\,V$ potential difference is applied across a wire of length $0.1\,m$, the drift speed of electrons is $2.5\times10^{-4}$ $ms^{-1}$. If the electron density in the wire is $8\times10^{28}\, m^{-3}$ the resistivity of the material is close to

The half life of a radioactive substance is $20\, minutes$. The time taken between $50\%$ decay and $87.5\%$ decay of the substance will be

A person is standing on a weighing-scale and observes that the reading is $60\,kg$ . He then suddenly jumps up and observes that reading goes to $70\,kg$ . Then his maximum upward acceleration is

Consider a spherical shell of radius $R$ at temperature $T$. The black body radiation inside it can be considered as an ideal gas of photons with internal energy per unit volume $u=\frac{U}{V} ? T^4$ and pressure $p=\frac{1}{3}\bigg(\frac{U}{V}\bigg)$ If the shell now undergoes an adiabatic expansion, the relation between $T$ and $R$ is

Consider an ideal gas confined in an isolated closed chamber. As the gas undergoes an adiabatic expansion, the average time of collision between molecules increases as $V^q$ , where $V$ is the volume of the gas. The value of $q$ is $\bigg(\gamma =\frac{C_p}{C_v}\bigg)$

A solid body of constant heat capacity $1 \, J/^{\circ}C$ is being heated by keeping it in contact with reservoirs in two ways (i) Sequentially keeping in contact with $2$ reservoirs such that each reservoir supplies same amount of heat. (ii) Sequentially keeping in contact with $8$ reservoirs such that each reservoir supplies same amount of heat. In both the cases, body is brought from initial temperature $100^{\circ}C$ to final temperature $200^{\circ}C$. Entropy change of the body in the two cases respectively, is

As an electron makes a transition from an excited state to the ground state of a hydrogen- like atom/ion

Two coaxial solenoids of different radii carry current $I$ in the same direction. Let $\vec{F}_1$ be the magnetic force on the inner solenoid due to the outer one and $\vec{F}_2$ be the magnetic force on the outer solenoid due to the inner one. Then,

A long cylindrical shell carries positive surface charge $\sigma$ in the upper half and negative surface charge $-\sigma$ in the lower half. The electric field lines around the cylinder will look like figure given in: (figures are schematic and not drawn to scale)

A thin disc of radius $b\, = \,2a$ has a concentric hole of radius '$a$' in it (see figure). It carries uniform surface charge '$\sigma$' on it. If the electric field on its axis at height '$h$' $(h < < a)$ from its centre is given as '$Ch$' then value of '$C$' is :

Across a metallic conductor of non-uniform cross section a constant potential difference is applied. The quantity which remains constant along the conductor is: