List of top Physics Questions

Half mole of an ideal monoatomic gas is heated at constant pressure of 1 atm from $20{^{\circ}C}$ to $90^{\circ}C$. Work done by gas is close to : ( Gas constant R = $8.31\, J\, /mol-K$)

Surface of certain metal is first illuminated with light of wavelength $\lambda_1 =350 \; nm$ and then, by light of wavelength $\lambda_2=54\, \; nm$. It is found that the maximum speed of the photo electrons in the two cases differ by a factor of $2$. The work function of the metal (in eV) is close to : (Energjr of photon = $\frac{1240}{\lambda (in \; nm)} eV$)

In a radioactive decay chain, the initial nucleus is $^{232}_{90}Th$ . At the end there are $6 \alpha$-particles and $4 \beta$-particles which are emitted. If the end nucleus, If $^{A}_{Z} X$ , $A$ and $Z$ are given by :

Three particles of masses $50\, g, 100\, g$ and $150\, g$ are placed at the vertices of an equilateral triangle of side $1\, m$ (as shown in the figure). The $(x, y)$ coordinates of the centre of mass will be :

Two masses $m$ and $\frac{m}{2}$ are connected at the two ends of a massless rigid rod of length $l$. The rod is suspended by a thin wire of torsional constant $k$ at the centre of mass of the rod-mass system(see figure). Because of torsional constant $k$, the restoring torque is $\tau =k\theta$ for angular displacement $\theta$. If the rod is rota ted by $\theta_0$ and released, the tension in it when it passes through its mean position will be:

Two wires $A$ & $B$ are carrying currents $I_1$ & $I_2$ as shown in the figure. The separation between them is $d$. A third wire $C$ carrying a current $I$ is to be kept parallel to them at a distance $x$ from A such that the net force acting on it is zero. The possible values of $x$ are :

The magnetic moment of an octahedral homoleptic Mn(II) complex is $5.9\, BM$. The suitable ligand for this complex is :

For a uniformly charged ring of radius $R$, the electric field on its axis has the largest magnitude at a distance $h$ from its centre. Then value of $h$ is :

Charge is distributed within a sphere of radius $R$ with a volume charge density $p (r) = \frac{A}{r^2} e^{-2r/a}$ where $A$ and $a$ are constants. If $Q$ is the total charge of this charge distribution, the radius $R$ is :

A copper wire is stretched to make it $0.5 \%$ longer. The percentage change in its electrical resistance if its volume remains unchanged is:

A potentiometer wire $AB$ having length $L$ and resistance $12\, r$ is joined to a cell $D$ of emf $\varepsilon$ and internal resistance $r$. A cell $C$ having $emf \, \varepsilon /2$ and internal resistance $3r$ is connected. The length $AJ$ at which the galvanometer as shown in fig. shows no deflection is :

A resistance is shown in the figure. Its value and tolerance are given respectively by :

A carnot engine takes 300 calories of heat at 500 K and rejects 150 calories of heat to the sink. The temperature of the sink is

Induction furnace uses ______ to produce heat

A mass falls from a height 'h' and its time of fall $'l'$ is recorded in terms of time period T of a simple pendulum. On the surface of earth it is found that I = 2T. The entire set up is taken on the surface of another planet whose mass is half of that of earth and radius the same. Same experiment is repeated and corresponding times noted as t' and T'.

Two objects of mass m each moving with speed u m/s collide at 90°, then final momentum is (assume collision is inelastic)

A rigid square loop of side 'a' and carrying current I$_2$ is lying on a horizontal surface near a long current I$_1$ carrying wire in the same plane as shown in figure. The net force on the loop due to wire will be :

The actual value of resistance $R$, shown in the figure is $30 \Omega $. This is measured in an experiment as shown using the standard formula $R = \frac{V}{I}$ , where $V$ and $I$ are the readings of the voltmeter and ammeter, respectively. If the measured value of $R$ is $5\%$ less, then the internal resistance of the voltmeter is :

Two plane mirrors arc inclined to each other such that a ray of light incident on the first mirror $(M_1)$ and parallel to the second mirror $(M_2)$ is finally reflected from the second mirror $(M_2)$ parallel to the first mirror $(M_1)$. The angle between the two mirrors will be :

Determine the charge on the capacitor in the following circuit :

Two identical breakers A and B contain equal volumes of two different liquids at $60^{\circ}C$ each and left to cool down. Liquid in A has density of $8 \times 10^2 \; kg/m^3$ and sp ecific heat o f 2000 J $kg^{-1} \; K^{-1}$ while liquid in B has density o f 103 kg m-3 and sp ecific heat o f 4000 J $kg^{-1} K^{-1}$. Which of the following best describes their temperature versus time graph schematically? (assume the emissivity of both the beakers to be the same)

In the circuit shown, the switch $S_1$ is closed at time $t = 0$ and the switch $S_2$ is kept open. At some later time $(t_0)$, the switch $S_1$ is opened and $S_2$ is closed. The behavious of the current $I$ as a function of time $'t'$ is given by :

A solid sphere and solid cylinder of identical radii approach an incline with the same linear velocity (see figure). Both roll without slipping all throughout. The two climb maximum heights $h_{sph}$ and $h_{cyl}$ on the incline. The ratio $\frac{h_{sph}}{h_{cyl}}$ is given by :

Maximum kinetic energy gained by the charged particle in the cyclotron is independent of

Which colour of the light has the longest wavelength?