List of top Physics Questions

A parallel plate capacitor having plate area 200 cm² and separation 2.0 mm holds a charge of 0.06 µC on applying a potential difference of 60 V. The dielectric constant of the material filled in between the plates is.
Two point charges, 4 µC and -3 µC (with no external field) are placed at (-6 cm, 0, 0) and (6 cm, 0, 0), respectively. The amount of work required to separate the two charges infinitely away from each other will be
In a series combination of capacitors connected across a battery
A charge of magnitude \(3 \times 10^{-7}\) C is located at a distance of 0.09 m from a point P. Obtain the work done in bringing a charge of \(2 \times 10^{-9}\) C from infinity to the point P.
Two coils ‘1’ and ‘2’ are placed close to each other as shown in the figure. Find the direction of induced current in coil ‘1’ in each of the following situations, justifying your answers:
Two coils ‘1’ and ‘2’ are placed

(a) Coil ‘2’ is moving towards coil ‘1’.
(b) Coil ‘2’ is moving away from coil ‘1’.
(c) The resistance connected with coil ‘2’ is increased keeping both the coils stationary.
The given diagram exhibits the relationship between the wavelength of the electromagnetic waves and the energy of photons associated with them. The three points P, Q, and R marked on the diagram may correspond respectively to:
relationship between the wavelength of the electromagnetic waves

A wooden block of mass M lies on a rough floor. Another wooden block of the same mass is hanging from the point O through strings as shown in the figure. To achieve equilibrium, the coefficient of static friction between the block on the floor and the floor itself is 

A 1 cm segment of a wire lying along the x-axis carries a current of 0.5 A along the \( +x \)-direction. A magnetic field \( \mathbf{B} = (0.4 \, \text{mT}) \hat{j} + (0.6 \, \text{mT}) \hat{k} \) is switched on in the region. The force acting on the segment is:

Show that the energy required to build up the current \( I \) in a coil of inductance \( L \) is \( \frac{1}{2} L I^2 \). 

In a two-level atomic system, the excited state is 0.2 eV above the ground state. Considering the Maxwell-Boltzmann distribution, the temperature at which 2% of the atoms will be in the excited state is _____ K. (up to two decimal places)
(Boltzmann constant \(k_B = 8.62 \times 10^{-5}\) eV/K)

At a particular temperature T, Planck's energy density of black body radiation in terms of frequency is \(\rho_T(\nu) = 8 \times 10^{-18} \text{ J/m}^3 \text{ Hz}^{-1}\) at \(\nu = 3 \times 10^{14}\) Hz. Then Planck's energy density \(\rho_T(\lambda)\) at the corresponding wavelength (\(\lambda\)) has the value \rule{1cm}{0.15mm} \(\times 10^2 \text{ J/m}^4\). (in integer) 
[Speed of light \(c = 3 \times 10^8\) m/s] 
(Note: The unit for \(\rho_T(\nu)\) in the original problem was given as J/m³, which is dimensionally incorrect for a spectral density. The correct unit J/(m³·Hz) or J·s/m³ is used here for the solution.)

The ratio of the density of atoms between the (111) and (110) planes in a simple cubic (sc) lattice is ____. (up to two decimal places)
The packing fraction for a two-dimensional hexagonal lattice having sides 2r with atoms of radii r placed at each vertex and at the center is _____. (up to two decimal places)
Consider a vector \(\mathbf{F} = \frac{1}{\pi}[-\sin y \hat{i} + x(1 - \cos y)\hat{j}]\). The value of the integral \(\oint \mathbf{F} \cdot d\mathbf{r}\) over a circle \(x^2 + y^2 = 1\) evaluated in the anti-clockwise direction is _____. (in integer)
A light beam given by \(\mathbf{E}(z, t) = E_{01} \sin(kz - \omega t)\hat{i} + E_{02} \sin(kz - \omega t + \frac{\pi}{6})\hat{j}\) passes through an ideal linear polarizer whose transmission axis is tilted by 60\(^\circ\) from x-axis (in x-y plane). If \(E_{01} = 4\) V/m and \(E_{02} = 2\) V/m, the electric field amplitude of the emerging light beam from the polarizer is ______ V/m. (up to two decimal places)
A wedge-shaped thin film is formed using soap-water solution. The refractive index of the film is 1.25. At near normal incidence, when the film is illuminated by a monochromatic light of wavelength 600 nm, 10 interference fringes per cm are observed. The wedge angle (in radians) is ______ \(\times 10^{-5}\). (in integer)
A gas absorbs \( 100 \, \text{J} \) of heat while performing \( 40 \, \text{J} \) of work on its surroundings. Calculate the change in internal energy of the gas.
A cylindrical pipe has a radius of \( 0.1 \, \text{m} \). If the speed of water flowing through the pipe is \( 2 \, \text{m/s} \), calculate the volume flow rate of water through the pipe.
Consider a chamber at room temperature (27 \(^\circ\)C) filled with a gas having a molecular diameter of 0.35 nm. The pressure (in Pascal) to which the chamber needs to be evacuated so that the molecules have a mean free path of 1 km is \rule{1cm{0.15mm} \(\times 10^{-5}\) Pa. (up to two decimal places)
(Boltzmann constant \(k_B = 1.38 \times 10^{-23}\) J/K)}
In an orthorhombic crystal, the lattice constants are 3.0 \AA, 3.2 \AA, and 4.0 \AA. The distance \(d_{101}\) between the successive (101) planes is \rule{1cm{0.15mm} \AA. (up to one decimal place)}
For a Zener diode as shown in the circuit diagram below, the Zener voltage \(V_Z\) is 3.7 V. For a load resistance (\(R_L\)) of 1 k\(\Omega\), a current \(I_1\) flows through the load. If \(R_L\) is decreased to 500 \(\Omega\), the current changes to \(I_2\). The ratio \(\frac{I_2}{I_1}\) is \rule{1cm{0.15mm}. (up to two decimal places)}
A NPN bipolar junction transistor (BJT) is connected in common emitter (CE) configuration as shown in the circuit diagram below. The amplifier is operating in the saturation regime. The collector-emitter saturation voltage (\(V_{CE,sat}\)) is 0.2 V. The current gain \(\beta = 100\). The maximum value of base resistance \(R_{BB}\) is \rule{1cm{0.15mm} k\(\Omega\). (in integer)}
A particle is moving with a constant angular velocity 2 rad/s in an orbit on a plane. The radial distance of the particle from the origin at time t is given by \(r = r_0 e^{2\beta t}\) where \(r_0\) and \(\beta\) are positive constants. The radial component of the acceleration vanishes for \(\beta = \) \rule{1cm{0.15mm} rad/s. (in integer)}
A planet rotates in an elliptical orbit with a star situated at one of the foci. The distance from the center of the ellipse to any foci is half of the semi-major axis. The ratio of the speed of the planet when it is nearest (perihelion) to the star to that at the farthest (aphelion) is \rule{1cm{0.15mm}. (in integer)}
One kg of water at 27\(^\circ\)C is brought in contact with a heat reservoir kept at 37\(^\circ\)C. Upon reaching thermal equilibrium, this mass of water is brought in contact with another heat reservoir kept at 47\(^\circ\)C. The final temperature of water is 47\(^\circ\)C. The change in entropy of the whole system in this entire process is \rule{1cm{0.15mm} cal/K. (up to two decimal places)
Take specific heat at constant pressure of water as 1 cal/(g K)}