List of top Physics Questions

Two short bar magnets of length $1\, cm$ each have magnetic moments $1.20 \,Am^2 $ and $1.00 \,Am^2 $ respectively. They are placed on a horizontal table parallel to each other with their $N$ poles pointing towards the south. They have a common magnetic equator and are separated by a distance of $20.0\, cm$. The value of the resultant horizontal magnetic induction at the mid-point $O$ of the line joining their centres is close to (Horizontal component of the earth's magnetic induction is $ 3.6 \times {10}^{-5} W b/m^2$
The amplitude of a damped oscillator decreases to $0.9$ times its original magnitude is $5\, s$. In another $10\, s$ it will decrease to a times its original magnitude, where $\alpha$ equals
The dimensions of angular momentum, latent heat and capacitance are, respectively.
The image of an illuminated square is obtained on a screen with the help of a converging lens. The distance of the square from the lens is $40\, cm$. The area of the image is $9$ times that of the square. The focal length of the lens is :
The supply voltage in a room is $120\, V$. The resistance of the lead wires is $6 \, \Omega$. A $60\, W$ bulb is already switched on. What is the decrease of voltage across the bulb, when a $240\, W$ heater is switched on in parallel to the bulb?
To establish an instantaneous current of $2 A$ through a $1 \mu F$ capacitor; the potential difference across the capacitor plates should be changed at the rate of :
Two balls of same mass and carrying equal charge are hung from a fixed support of length $l$. At electrostatic equilibrium, assuming that angles made by each thread is small, the separation, $x$ between the balls is proportional to :
Two blocks of masses $m$ and $M$ are connected by means of a metal wire of cross-sectional area $A$ passing over a frictionless fixed pulley as shown in the figure. The system is then released. If $M \,= \,2 m$, then the stress produced in the wire is:
Two small equal point charges of magnitude $q$ are suspended from a common point on the ceiling by insulating mass less strings of equal lengths. They come to equilibrium with each string making angle $\theta$ from the vertical. If the mass of each charge is $m$, then the electrostatic potential at the centre of line joining them will be $\left(\frac{1}{4\pi\,\in_{0}}=k\right).$
A sonometer wire of length $114\, cm$ is fixed at both the ends. Where should the two bridges be placed so as to divide the wire into three segments whose fundamental frequencies are in the ratio $1 : 3 : 4$ ?

On a linear temperature scale $Y$, water freezes at $-160^{\circ}$ $Y$ and boils at $-50^{\circ}\, Y$. On this $Y$ scale, a temperature of $340\, K$ would be read as :
(water freezes at $273\, K$ and boils at $373\, K$)

Select the correct statement from the following
The surface charge density of a thin charged disc of radius $R$ is $\sigma$. The value of the electric field at the centre of the disc is $\frac{\sigma}{2 \in_{0}} \cdot$ With respect to the field at the centre, the electric field along the axis at a distance $R$ from the centre of the disc :
This question has Statement I and Statement II. Of the four choices given after the Statements, choose the one that best describes the two Statements. Higher the range, greater is the resistance of ammeter. To increase the range of ammeter, additional shunt needs to be used across it.

Two rings of radius \( R \) and \( nR \) made of same material have the ratio of moment of inertia about an axis passing through the centre is 1 : 8. The value of \( n \) is a

A light inextensible string that goes over a smooth fixed pulley as shown in the figure connects two blocks of masses 0.36 kg and 0.72 kg. Taking \( g = 10 \, \text{m/s}^2 \), find the work done (in joules) by the string on the block of mass 0.36 kg during the first second after the system is released from rest. 

Figure shows a copper rod joined to a steel rod. The rods have equal length and equal cross-sectional area. The free end of the copper rod is kept at 0°C and that of steel rod is kept at 100°C. Find the temperature of the junction of the rod. 
Conductivity of copper = \( 390 \, \text{W/m°C} \)
Conductivity of steel = \( 46 \, \text{W/m°C} \)

A cube is subjected to a uniform volume compression. If the side of the cube decreases by 2%, the bulk strain is a

A disc is performing pure rolling on a smooth stationary surface with constant angular velocity as shown in the figure. At any instant, for the lower most point of the disc
 

There is a shell of mass \( M \) and density of the shell is uniform. The work done to take a point mass from point A to B is \( [AB = r] \) 
 

In the circuit shown in figure, the potential difference between points A and B is 16 V. The current passing through \( 2 \Omega \) resistance will be 
 

The circuit is equivalent to 

Which of the following electromagnetic radiations has the smallest wavelength?
Eddy currents are produced when
Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area \( A = 10 \, \text{cm}^2 \) and length 20 cm. If one of the solenoids has 300 turns and the other 400 turns, their mutual inductance is