List of top Physics Questions

Three blocks \( M_1, M_2, M_3 \) (\( M_1>M_2>M_3 \)) lie on a plane. The angle of inclination \( \theta \) is increased. If the coefficient of friction is the same for all, then:
Three blocks M1,M2,M3
A bar of mass \(m\) resting on a smooth horizontal plane starts moving due to a constant force \(F\). In the process of its rectilinear motion the angle \(\theta\) between the direction of this force and the horizontal varies as \(\theta = kx\), where \(k\) is a constant and \(x\) is the distance traversed by the bar from its initial position. The velocity \(v(\theta)\) of the bar as a function of the angle \(\theta\) is:
A particle is moving along x-axis with velocity \( v = \frac{1}{1 + \beta t} \). At time \( t = 0 \), the particle is at \( x = 0 \). The displacement as a function of time is:
Two electric dipoles of dipole moments 1.2 × 10–30 C-m and 2.4 × 10–30 C-m are placed in two different uniform electric fields of strength 5 × 104 NC–1 and 15 × 104 NC–1 respectively. The ratio of maximum torque experienced by the electric dipoles will be 1:x. The value of x is _______
A plane electromagnetic wave of wave interface 10W/m2 strikes a small mirror of area 20 cm2, held perpendicular to the approaching wave. The radiation force on the mirror will be:
Area of the cross-section of a wire is measured using a screw gauge. The pitch of the main scale is 0.5 mm. The circular scale has 100 divisions and for one full rotation of the circular scale, the main scale shifts by two divisions. The measured readings are listed below.
 
Measurement conditionMain scale readingCircular scale reading
Two arms of gauge touching each other without wire0 division4 divisions
Attempt-1: With wire4 divisions
20 divisions
Attempt-2: With wire
4 divisions
16 divisions

What are the diameter and cross-sectional area of the wire measured using the screw gauge?
 
The maximum number of TV signals that can be transmitted along a co-axial cable is:
Output of the following logic circuit is:
logic circuit
The graph of \( \ln \left( \frac{R}{R_0} \right) \) versus \( \ln A \), where \( R \) is the radius of a nucleus, \( A \) its mass number, and \( R_0 \) a constant, is:
The metal which has the highest work function in the following is:
For a hydrogen atom, the energy of a stationary electron is given by \( E_n = -\frac{13.6}{n^2} \, \text{eV} \). The energy required to excite the electron to the second excited state and to the ionized state are:
An electromagnetic wave travels along the z-axis. At a certain point in space, the electric field is \( 8.7 \, \text{Vm}^{-1} \) along the x-axis. What is the magnitude of the magnetic field along the y-axis?
A beam of light with intensity \( 10^5 \, \text{Nm}^{-2} \) and cross-sectional area \( 20 \, \text{cm}^2 \) is incident on a fully reflective surface at an angle of \( 45^\circ \). Find the force exerted by the beam on the surface.
If the average power per unit area delivered by an electromagnetic wave is \( 9240 \, \text{Wm}^{-2} \), what is the amplitude of the magnetic field in the wave?
A coil of inductance \( 0.1 \, \text{H} \) and resistance \( 110 \, \Omega \) is connected to an AC source of \( 110 \, \text{V}, 350 \, \text{Hz} \). What is the phase difference between the voltage maximum and the current maximum?
A capacitor \( C_1 = 1\, \mu\text{F} \) is charged using a 9 V battery. It is then disconnected and connected to capacitors \( C_2 = 2\, \mu\text{F} \) and \( C_3 = 3\, \mu\text{F} \) as shown. Find the charge on \( C_3 \) after equilibrium is reached.
A capacitor C1 = 1µF is charged using a 9 V battery
Two positive charges of 10 \( \mu \text{C} \) and 12 \( \mu \text{C} \) are 10 cm apart. What is the work done in bringing them 6 cm closer?
Two infinite wires are placed at \( x = -2 \, \text{cm} \) and \( x = 1 \, \text{cm} \) along the y-axis, each carrying current upward. An electron is fired from the origin at \( 45^\circ \) to the x-axis with speed \( U \). The force on the electron at the moment of launch is:
(\( B_0 \) is the field at origin due to the wire at \( x = 1 \, \text{cm} \))
Two electrons \( e_1 \) and \( e_2 \), both having mass \( m \) and charge \( q \), are projected perpendicular to a magnetic field \( B \). If the kinetic energy of \( e_1 \) is twice that of \( e_2 \), what is the relation between their rotation frequencies \( f_1 \) and \( f_2 \)?
A compass needle oscillates 20 times per minute at a location with dip \( 45^\circ \) and magnetic field \( B_1 \). It oscillates 30 times per minute at another location where dip is \( 30^\circ \) and field is \( B_2 \). Find the ratio \( \frac{B_1}{B_2} \).
Current density in a cylindrical wire of radius \( R \) varies with radial distance as \( \beta (r + r^2) \). What is the current through the shaded section (sector angle \( \pi/6 \)) of the wire as shown in the figure?
Current density in a cylindrical wire of radius R
A cell supplies currents of 1 A and 0.5 A through resistors of 2.5 \( \Omega \) and 10 \( \Omega \), respectively. The internal resistance of the cell is:
The number of vibrational degrees of freedom for a diatomic molecule is:
A Carnot engine operates between a source and sink. The efficiency of the engine is 40\% and the sink temperature is \( 27^\circ \text{C} \). If the efficiency is to be increased to 50\%, then by how much should the source temperature be increased?
A car engine has a power of 20 kW and runs for 1 hour. If the thermal efficiency is 40\% and ambient temperature is 300 K, then what is the energy generated by fuel combustion?