List of top Physics Questions

A diverging lens of focal length 20 cm and a converging lens of focal length 30 cm are placed 15 cm apart with their principal axes coinciding. Where should an object be placed on the principal axis so that its image is formed at infinity?
A sinusoidal voltage of amplitude \( 25 \) V and frequency \( 50 \) Hz is applied to a half-wave rectifier using a P-N junction diode. No filter is used, and the load resistor is \( 1000\Omega \). The forward resistance \( R_f \) of the ideal diode is \( 10\Omega \). The percentage rectifier efficiency is:

Consider an electric field \( \mathbf{E} = E_0 \hat{x} \), where \( E_0 \) is a constant. The flux through the shaded area (as shown in the figure) due to this field is: 
 

A flask contains a monoatomic and a diatomic gas in the ratio of \( 4:1 \) by mass at a temperature of \( 300K \). The ratio of average kinetic energy per molecule of the two gases is:

An element of \( 0.05 \) m is placed at the origin, carrying a large current of \( 10 A \). The magnetic field at a perpendicular distance of \( 1 \) m is: 
 

The potential energy of a particle \( U(x) \) executing simple harmonic motion is given by:
The equation of a wave on a string of linear mass density \( 0.04 \) kg/m is given by:
\[ y = 0.02 \sin 2\pi \left( \frac{t}{0.04} - \frac{x}{0.50} \right) \] The tension in the string is:
Water falls from a \( 40 \) m high dam at the rate of \( 9 \times 10^4 \) kg per hour. Fifty percent of gravitational potential energy can be converted into electrical energy. The number of \( 100W \) lamps that can be lit is:
The pressure inside a tyre is 4 times that of the atmosphere. If the tyre bursts suddenly at temperature \( 300K \), what will be the new temperature?
The ozone layer in the atmosphere absorbs:
A ball of radius \( r \) and density \( \rho \) falls freely under gravity through a distance \( h \) before entering water. The velocity of the ball does not change even on entering water. If the viscosity of water is \( \eta \), the value of \( h \) is given by:
\includegraphics[width=0.5\linewidth]{28.png}

Equipotential surfaces are shown in the figure. The electric field strength will be: 
 

A square frame of side \( 10 \) cm and a long straight wire carrying current \( 1A \) are in the plane of the paper. Starting from close to the wire, the frame moves towards the right with a constant speed of \( 10 \) m/s (see figure). The induced EMF at the time the left arm of the frame is at \( x = 10 \) cm from the wire is: 
 

In YDSE, how many maximas can be obtained on a screen, including central maxima, on both sides of the central fringe if \( \lambda = 3000\) Å, \( d = 5000\) Å?
A force \( \mathbf{F} = \alpha \hat{i} + 3 \hat{j} + 6 \hat{k} \) is acting at a point \( \mathbf{r} = 2 \hat{i} - 6 \hat{j} - 12 \hat{k} \). The value of \( \alpha \) for which angular momentum about the origin is conserved is:
An electron (mass = \( 9 \times 10^{-31} \) kg, charge = \( 1.6 \times 10^{-19} \) C) moving with a velocity of \( 10^6 \) m/s enters a magnetic field. If it describes a circle of radius \( 0.1 \) m, then the strength of the magnetic field must be:
The force between two short bar magnets with magnetic moments \( M_1 \) and \( M_2 \) whose centers are \( r \) meters apart is 8 N when their axes are in the same line. If the separation is increased to \( 2r \), the force between them is reduced to:
A given ray of light suffers minimum deviation in an equilateral prism \( P \). Additional prisms \( Q \) and \( R \) of identical shape and of the same material as \( P \) are now added as shown in the figure. The ray will now suffer:
\includegraphics[width=0.5\linewidth]{31.png}
An \( \alpha \)-particle of 10 MeV collides head-on with a copper nucleus (\( Z = 29 \)) and is deflected back. The minimum distance of approach between the centers of the two is:
A car moves at a speed of \( 20 { m/s} \) on a banked track and describes an arc of a circle of radius \( 40\sqrt{3} \) m. The angle of banking is: (Take \( g = 10 { m/s}^2 \))
What will be the maximum speed of a car on a road turn of radius 30m if the coefficient of friction between the tyres and the road is 0.4? (Take \( g = 9.8 { m/s}^2 \))
A person aiming to reach the exactly opposite point on the bank of a stream is swimming with speed of \( 0.5 \) m/s at an angle of \( 120^\circ \) with the direction of flow of water. The speed of water in the stream is:
Write the principle of Wheatstone's Bridge. Find the current measured by the ammeter in the given circuit diagram.
Explain Biot-Savart law and find the unit of \( \mu_0 \) with the help of the Biot-Savart equation.
A convex lens has power \( P \). It is cut into two halves along its principal axis. Further, one piece (out of the two halves) is cut into two halves perpendicular to the principal axis (as shown in figure). Choose the incorrect option for the reported pieces.
\includegraphics[width=0.5\linewidth]{27.png}