List of top Physics Questions

A train is moving slowly on a straight track with a constant speed of $2\, ms^{-1}$ passenger in that train starts walking at a steady speed of $2\, ms^{-1}$ to the back of the train in the opposite direction of the motion of the train. So to an observer standing on the platform directly in front of that passenger, the velocity of the passenger appears to be
A lead bullet of unknown mass is fired with a speed of 180 ms-1 into a tree in which it stops. Assuming that in this process two-third of heat produced goes into the bullet and one- third into wood. The temperature of the bullet rises by (Specific heat of lead $ =\text{ }0.120\text{ }J{{g}^{-1}}{{C}^{-1}} $ )
In sine wave, minimum distance between $ 2 $ particles always having same speed is
$ U $ is the $ PE $ of an oscillating particle and $ F $ is the force acting on it at a given instant. Which of the following is true ?
Four wires of the same material are stretched by the same load. Which one of them will elongate most if their dimensions are as follows
In the figures shown below
If 200 MeV of energy is released in the fission of nucleus of $ _{92}{{U}^{235}}, $ the number of nuclei that undergo fission to produce energy of 10 kWh in 1 s
Which of the following statement is false for the properties of electromagnetic waves?
A block of mass $m$ is in contact with the cart $C$ as shown in the figure. The coefficient of static friction between the block and the cart is $\mu$. The acceleration $\alpha$ of the cart that will prevent the block from falling satisfies
A particle moves in $x-y$ plane according to rule $x = a\,\sin\omega t$ and $y = a \,\cos\omega t$. The particle follows
A vibration magnetometer placed in magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of $2$ sec in earth's horizontal magnetic field of $24$ microtesla. When a horizontal field of $18$ microtesla is produced opposite to the earth's field by placing a current carrying wire, the new time period of magnet will be
The mass of a $^7_3$Li nucleus is $0.042\, u$ less than the sum of the masses of all its nucleons. The binding energy per nucleon of $^7_3$Li nucleus is nearly
A common emitter amplifier has a voltage gain of $50$ , an input impedance of $100 \Omega$ and an output impedance of $200 \Omega$ The power gain of the amplifier is
A cylindrical metallic rod in thermal contact with two reservoirs of heat at its two ends conducts an amount of heat $Q$ in time $t$. The metallic rod is melted and the material is formed into a rod of half the radius of the original rod. What is the amount of heat conducted by the new rod when placed in thermal contact with the two reservoirs in time $t$ ?
A tuning fork of frequency $512\, Hz$ makes $4$ beats per second with the vibrating string of a piano. The beat frequency decreases to $2$ beats per sec when the tension in the piano string is slightly increased. The frequency of the piano string before increasing the tension was
A ray of light travelling in a transparent medium of refractive index $ \mu $, falls on a surface separating the medium from air at an angle of incidence of 45$^{\circ}$. For which of the following value of $ \mu $. the ray can undergo total internal reflection?
Electromagnets are made of soft iron because soft iron has
A galvanometer has a coil of resistance $100\, ohm$ and gives a full scale deflection for $30\, mA$ current. If it is to work as a voltmeter of $30\, volt$ range, the resistance required to be added will be
A ball moving with velocity $2\, m/s$ collides head on with another stationary ball of double the mass. If the coefficient of restitution is $0.5$, then their velocities $(in\, m/s)$ after collision will be
A particle of mass $M$, starting from rest, undergoes uniform acceleration. If the speed acquired in time $T$ is $V$, the power delivered to the particle is
A condenser of capacity $C$ is charged to a potential difference of $V_1$. The plates of the condenser are then connected to an ideal inductor of inductance $L$. The current through the inductor when the potential difference across the condenser reduces to $V_2$ is
A current loop consists of two identical semicircular parts each of radius $R$, one lying in the $x-y$ plane and the other in $x-z$ plane. If the current in the loop is $i$. The resultant magnetic field due to the two semicircular parts at their common centre is
A circular disk of moment of inertia it is rotating in a horizontal plane, about its symmetry axis, with a constant angular speed $\omega_i$. Another disk of moment of inertia $I_b$ is dropped coaxially onto the rotating disk. Initially the second disk has zero angular speed. Eventually both the disks rotate with a constant angular speed $\omega_f$. The energy lost by the initially rotating disc to friction is
The resistance of 1 N solution of acetic acid is 250 $\Omega$, when measured in a cell of cell constant $1.15 cm ^{-1}$. The equivalent conductance (in $ohm^{-1} cm^2 equiv^{-1}) $of 1 N acetic acid is
Two springs of spring constants $k_{1}$ and $k_{2}$ are joined in series and a mass $m$ is attached to them as shown in figure. The time-period of oscillations of the springs is