List of top Physics Questions

The temperature of the surface of Sun is 6000 K. The wavelength corresponding to the maximum energy is nearly (Wien's constant, \( b = 2.89 \times 10^{-3} \, \text{mK} \))

During an adiabatic process of a monatomic gas, the relation between absolute temperature (\( T \)) and pressure (\( P \)) is \( P \propto T^X \). The value of \( X \) is

A drilling machine of power \(1~\text{kW}\) is used for 5 minutes to drill a hole in a \(10~\text{kg}\) metal block. If 40% of the work done by the machine is wasted as heat, the rise in temperature of the metal block is nearly (specific heat capacity of the metal = \(420~\text{J\,kg}^{-1}\text{K}^{-1}\))

A gas is compressed from a volume of \(23~\text{m}^3\) to \(17~\text{m}^3\) at a constant pressure of \(50~\text{Nm}^{-2}\). If \(50~\text{J}\) of heat is added to the gas, then the change in its internal energy is

If the percentage increase in the pressure of a given mass of gas in a container at constant temperature is 100%, then its volume

If the speed of a wave doubles as it passes from shallow water into deeper water, its wavelength will be

A tank is filled with benzene to a height of \(120~\text{mm}\). The apparent depth of a needle lying at the bottom of the tank, as seen through a microscope, is found to be \(80~\text{mm}\). The refractive index of benzene is

In Young’s double slit experiment, if the distance between the two slits is decreased by 20% and the distance between the slits and the screen is increased by 20%, then the percentage increase in the fringe width is

Three charges \(+Q\), \(q\), \(+Q\) are placed respectively, at distances \(0\), \(\frac{d}{2}\), and \(d\) from the origin on the x-axis. If the net force experienced by \(+Q\) placed at \(x = 0\) is zero, then the value of \(q\) is

A conducting sphere of radius \(R\) carrying a charge \(Q\) lies concentrically inside an uncharged conducting shell of radius \(2R\). If they are joined by a metal wire, then the charge flowing to the shell and the amount of heat produced are respectively:

An uncharged parallel plate capacitor with dielectric constant \(K\) is connected to a similar air-cored capacitor which is charged to a potential \(V_0\). If the common potential is \(V\), then the value of \(K\) is

If \(n\), \(e\), \(\tau\), and \(m\) represent the concentration, the charge, the relaxation time, and the mass of an electron in a metal, then the resistance of a wire made of the metal of length \(l\) and cross-sectional area \(A\) is:

In a potentiometer experiment, the balancing length with a cell is \(240~\text{cm}\). On shunting the cell with \(2~\Omega\), the balancing length becomes \(120~\text{cm}\). The internal resistance of the cell is

To generate the high magnetic fields, the synchrotron uses

If the magnetic field is along the positive y-axis and the electron is moving along the positive x-axis, the direction of force on the electron is

A bar magnet of length \(0.1~\text{m}\) and magnetic moment of \(5~\text{Am}^2\) is placed in a uniform magnetic field of intensity \(0.4~\text{T}\), with its axis making an angle of \(60^\circ\) with the field. The torque on the magnet is

Changing magnetic fields can set up current loops in nearby metal bodies. They dissipate electrical energy as heat. Such currents are called

A resistor of \(50~\Omega\), an inductor and a capacitor are connected in series to an AC source of peak voltage \(200\sqrt{2}~\text{V}\).
When the capacitor alone is removed, current lags voltage by \(37^\circ\).
When the inductor alone is removed, current leads voltage by \(37^\circ\).
The power dissipated in the LCR circuit is:

The efficiency of a bulb of \(1000~\text{W}\) is \(6%\). The peak value of the magnetic field produced by the electromagnetic radiation from the bulb at a distance of \(1~\text{m}\) is: \[ \left( \frac{1}{4\pi \varepsilon_0} = 9 \times 10^9~\text{Nm}^2\text{C}^{-2} \right) \]

Two photons each of energy \(2~\text{eV}\) incident simultaneously on a photosensitive material of work function \(3~\text{eV}\). The maximum kinetic energy of the emitted photoelectrons is

An electron in the ground state of hydrogen atom absorbs \(10.2~\text{eV}\) energy. The orbital angular momentum of the electron increases by

If the speed of light was half the present value, the energy released in a nuclear reaction decreases by

In the given logic circuit, if A and B are the inputs, then P and Q are respectively
\

An oscillator is an amplifier with

A message signal of frequency \(20~\text{kHz}\) and peak voltage \(20~\text{V}\) is used to modulate a carrier of peak voltage \(100~\text{V}\). The modulation index is