List of top Physics Questions

The temperatures of the source and sink of a Carnot’s heat engine are 27$^\circ$C and 127$^\circ$C respectively. If the absolute temperature of the sink is decreased by 10%, the efficiency of the engine:
Sixteen point charges each of charge \( q \) are placed on the circumference of a circle of radius \( r \) with equal angular spacing. If one of the charges is removed, then the net electric field at the centre of the circle is \( \varepsilon_0 \) (where \( \varepsilon_0 \) is the permittivity of free space). What is the net electric field at the centre?
The ratio of the values of acceleration due to gravity at heights \( h_1 \) and \( h_2 \) from the surface of the earth is \( 16:9 \). If height \( h_1 = 2R_E \), then \( h_2 \) is:
The height of water level in a tank of uniform cross-section is 5 m. The volume of the water leaked in 5 s through a hole of area \(2.4~mm^{2}\) made at the bottom of the tank is (Assume the level of the water in the tank remains constant and acceleration due to gravity \(=10~ms^{-2}\))

The resistance of a wire is \(2.5 \Omega\) at a temperature \(373 K\). If the temperature coefficient of resistance of the material of the wire is \(3.6 \times 10^{-3} K^{-1}\), its resistance at a temperature \(273 K\) is nearly: 

A body of mass 'm' tied to one end of a string is whirled in a vertical circle of radius 'R' with zero tension in the string at its highest point. The angle made by the string with the vertical when the kinetic energy of the body becomes half of its maximum kinetic energy is:

If Planck's constant is \( 6.63 \times 10^{-34} \) Js, then the slope of a graph drawn between cut-off voltage and frequency of incident light in a photoelectric experiment is:

The current gain of a transistor in common emitter configuration is 45. If the resistances in collector and base sides of the circuit are 4.5 kΩ and 900 Ω, the voltage gain of the amplifier is:
An electron falling freely under the influence of gravity enters a uniform magnetic field directed towards south. The electron is initially deflected towards?
If three sources of sound of frequencies \( (n-1), n, (n+1) \) are vibrated together, the number of beats produced and heard per second respectively are:
For a combination of two convex lenses of focal lengths \( f_1 \) and \( f_2 \) to act as a glass slab, the distance of separation between them is:
Two particles of charges in the ratio \( 1:2 \) and masses in the ratio \( 2:3 \) moving along a straight line enter a uniform magnetic field at right angles to the direction of the field. If the radii of the circular paths of the particles in the magnetic field are in the ratio \( 3:4 \), then the ratio of the initial linear momenta of the two particles is:
The energy stored in a coil of inductance 80 mH carrying a current of 2.5 A is:
For the displacement current through the plates of a parallel plate capacitor of capacitance 30 µF to be 150 µA, the potential difference across the plates of the capacitor has to vary at the rate of:

A body thrown vertically upwards from the ground reaches a maximum height ‘h’. The ratio of the kinetic and potential energies of the body at a height 40\% of h from the ground is

The ratio between electric field energy density and magnetic field energy density of an electromagnetic wave, in its region is:
Two equal resistances are connected in the two gaps of a meter bridge. If the resistance in the right gap is doubled, then the change in the balancing length is:
An inductor of inductive reactance \( R \), a capacitor of capacitive reactance \( 2R \), and a resistor of resistance \( R \) are connected in series to an AC source. The power factor of the series LCR circuit is?
A block of mass \( m \) with an initial kinetic energy \( E \) moves up an inclined plane of inclination \( \theta \). If \( \mu \) is the coefficient of friction between the plane and the body, the work done against friction before coming to rest is:
The efficiency of a bulb of power \( 60 \) W is \( 16\% \). The peak value of the electric field produced by the electromagnetic radiation from the bulb at a distance of \( 2 \) m from the bulb is? \[ \left(\frac{1}{4\pi \epsilon_0} = 9 \times 10^9 \text{ Nm}^2\text{C}^{-2} \right) \]
The capacitance of a parallel plate capacitor is 1.5 µF. If the distance between the plates is halved and the space between the plates is filled with a medium of dielectric constant 3, then the new capacitance is:
Three capacitors of capacitances 10 \(\mu\)F, 5 \(\mu\)F and 20 \(\mu\)F are connected in series with a 14 V dc supply. The charge on 5 \(\mu\)F capacitor is
The relation between the charge \( Q \) (in coulombs) passing through a resistor of resistance 200 \(\Omega\) and the time of flow of charge \( t \) (in seconds) is \( Q = 3t - 4t^2 \). The total heat produced in the resistor up to the time when instantaneous current becomes zero is:
A solid sphere and a disc of same mass \(M\) and radius \(R\) are kept such that their curved surfaces are in contact and their centers lie along the same horizontal line. The moment of inertia of the two body system about an axis passing through their point of contact and perpendicular to the plane of the disc is:
The internal and external diameters of a hollow cylinder measured with vernier calipers are (5.73 \(\pm\) 0.01) cm and (6.01 \(\pm\) 0.01) cm respectively. Then the thickness of the cylinder wall is