List of top Physics Questions

Friction can be reduced by changing from

For safety, the fuse wire used in the mains for household supply of electricity must be made of metal having

What is the cause for twinkling of stars?

A jet engine works on the principle of conservation of which of the following?

The speed of light will be the minimum while passing through which of the following?

A Solar Eclipse will take place when

What should be the minimum height of a plane mirror required to view the full image of a person who is 6 feet tall?

A convex lens $'A'$ of focal length $20\, cm$ and a concave lens $'B'$ of focal length $5\, cm$ are kept along the same axis with a distance $'d'$ between them. If a parallel beam of light falling on $'A'$ leaves $'B'$ as a parallel beam, then the distance $'d'$ in cm will be :

A small object is placed at the center of a large evacuated hollow spherical container. Assume that the container is maintained at $0\, K$. At time $t =0$, the temperature of the object is $200 \,K$. The temperature of the object becomes $100 \,K$ at $t = t _{1}$ and $50\, K$ at $t = t _{2}$.Assume the object and the container to be ideal black bodies. The heat capacity of the object does not depend on temperature. The ratio \(\left( \frac{t _{2} }{ t _{1}}\right)\) is______

Which of the following pairs of substances have the same values of specific heat?

In the Young's double slit experiment a monochromatic source of wavelength $\lambda$ is used. The intensity of light passing through each slit is $I _{0}$. The intensity of light reaching the screen $S _{ C }$ at a point $P$, a distance $X$ from $O$ is given by (Take $d < < D$ )

A capacitor of capacitance $'C'$, is connected across an ac source of voltage $V$, given by $V = V _{0} \sin \omega t$ The displacement current between the plates of the capacitor, would then be given by:

A projectile is thrown from a point $O$ on the ground at an angle $45^{\circ}$ from the vertical and with a speed $5 \sqrt{2} \,m / s$. The projectile at the highest point of its trajectory splits into two equal parts. One part falls vertically down to the ground, $05\, s$ after the splitting. The other part, $t$ seconds after the splitting, falls to the ground at a distance $x$ meters from the point $O$. The acceleration due to gravity $g =10 \,m / s ^{2}$.
The value of $x$ is ______

Eight drops of mercury of equal radii combine to form a big drop. The capacitance of a bigger drop as compared to each smaller drop is

Two thin biconvex lenses have focal lengths $f _{1}$ and $f _{2} .$ A third thin biconcave lens has focal length of $f_{3} .$ If the two biconvex lenses are in contact, the total power of the lenses is $P _{1}$. If the first convex lens is in contact with the third lens, the total power is $P _{2}$. If the second lens is in contact with the third lens, the total power is $P _{3}$ then

In the given figure, a mass \(M\) is attached to a horizontal spring which is fixed on one side to a rigid support. The spring constant of the spring is \(k\). The mass oscillates on a frictionless surface with the time period \(T\) and amplitude \(A\). When the mass is in an equilibrium position, as shown in the figure, another mass \(m\) is gently fixed upon it. The new amplitude of oscillation will be : 

A toroid with thick windings of $N$ turns has inner and outer radii $R_{1}$ and $R_{2}$ respectively. If it carries certain steady current I, the variation of the magnetic field due to the toroid with radial distance is correctly graphed in

The resistance of $0.01 \,m \,KCl$ solution at $298\, K$ is $1500\, \Omega$. If the conductivity of $0.01\, m \,KCl$ solution at $298\, K$ is $0.146 \,\times \,10^{-3}\, S \,cm ^{-1} .$ The cell constant of the conductivity cell in $cm ^{-1}$ is

In the circuit, a metal filament lamp is connected in series with a capacitor of capacitance $C\, \mu F$ across a $200\, V , 50\, Hz$ supply. The power consumed by the lamp is $500\, W$ while the voltage drop across it is $100\, V$. Assume that there is no inductive load in the circuit. Take $r m s$ values of the voltages. The magnitude of the phase-angle (in degrees) between the current and supply voltage is $\phi $. Assume, $\pi \sqrt{3} \approx 5$

A pendulum consists of a bob of mass $m =0.1\, kg$ and a massless inextensible string of length $L =1.0 \,m $. It is suspended from a fixed point at height $H =0.9 \,m$ above a frictionless horizontal floor Initially, the bob of the pendulum is lying on the floor at rest vertically below the point of suspension. A horizontal impulse $P =0.2\, kg - m / s$ is imparted to the bob at some instant. After the bob slides for some distance, the string becomes taut and the bob lifts off the floor. The magnitude of the angular momentum of the pendulum about the point of suspension just before the bob lifts off is $J \,kg - m ^{2} / s$. The kinetic energy of the pendulum just after the lift-off is $K$ Joules.

Two point charges $- Q$ and \(\frac{+ Q }{ \sqrt{3}}\) are placed in the $xy$-plane at the origin $(0,0)$ and a point $(2,0)$, respectively, as shown in the figure. This results in an equipotential circle of radius $R$ and potential $V=0$ in the $x y$-plane with its center at $(b, 0)$. All lengths are measured in meters 

In the circuit shown below, the switch $S$ is connected to position $P$ for a long time so that the charge on the capacitor becomes $q _{1}\, \mu C$. Then $S$ is switched to position $Q$. After a long time, the charge on the capacitor is $q _{2}\, \mu C$

 

A projectile is thrown from a point $O$ on the ground at an angle $45^{\circ}$ from the vertical and with a speed $5 \sqrt{2} \,m / s$. The projectile at the highest point of its trajectory splits into two equal parts. One part falls vertically down to the ground, $05\, s$ after the splitting. The other part, $t$ seconds after the splitting, falls to the ground at a distance $x$ meters from the point $O$. The acceleration due to gravity $g =10 \,m / s ^{2}$.

A slit of width 'a' is illuminated by red light of wavelength $6500 ?$. If the first diffraction minimum falls at $30 ?$, then the value of ' $a$ ' is