List of top Physics Questions

Four closed surfaces and corresponding charge distributions are shown below. The respective electric fluxes through the surfaces $ S_1, S_2, S_3, S_4 $ are $ \Phi_1, \Phi_2, \Phi_3, \Phi_4 $. Then, which of the following is correct?

The dimension of force constant is

Consider a viscous fluid having uniform density $ \rho $ and coefficient of viscosity $ \eta $. Two solid spheres with radius $ R_1 $ and $ R_2 $ fall into this liquid and acquire terminal velocities of $ V $ and $ 8V $ respectively. If the densities of the two spheres are $ 2\rho $ and $ 3\rho $ respectively, then $ R_1 $ is equal to $ R_2 $?

Two very long, straight, and insulated wires are kept at a 90° angle from each other in the x-y plane as shown in the figure. These wires carry equal currents of magnitude $ I $, whose directions are shown in the figure. The net magnetic field at point P will be:

1 gm of ice at 0°C is mixed with 1 gm of water at 100°C. At thermal equilibrium, the temperature of the mixture will be:

At temperature $ T $, the probability of ideal gas molecules with mass $ m $ having speed $ v $ is given by $ P(v) $. Two quantities $ I_1 $ and $ I_2 $ are defined in terms of $ P(v) $ as follows:
\[ I_1 = \int_0^\infty P(v) v^3 \, dv \quad \text{and} \quad I_2 = \int_0^\infty P(v) v \, dv \] Which of the following relationship is true?

In a Doppler effect experiment, initially an observer and the source are moving towards each other with equal speeds. The observed frequency in this case is found to be $ f_0 $. The observed frequency once they cross each other is found to be $ f' $. If $ f $ is the frequency at the source, $ f' $ is equal to:

Consider two radioactive materials A and B. When A decays into 6.25 percent of its original amount, B decays into 25 percent of its original amount. The ratio of their decay constants $ \lambda_A $ and $ \lambda_B $ is:

A block of mass 300 g is kept stationary on a smooth inclined plane by applying a minimum horizontal force $ F = \sqrt{a} \, N $ as shown in the figure. The value of $ a $ is (Take $ g = 10 \, \text{m/s}^2 $):

The ratio of specific heats $ \frac{C_P}{C_V} $ in terms of degrees of freedom (n) is given by:

In the uranium radioactive series the initial nucleus is $^{238}U$ and the final nucleus is $^{206}Pb$. When the uranium nucleus decays to lead, the number of $\alpha$-particles and $\beta$-particles emitted respectively are:

A series R-C combination is connected to an AC voltage of angular frequency $ \omega = 1000 $ rad/s. If the impedance of the RC circuit is $ R/\sqrt{2} $, the time constant (in milliseconds) of the circuit is:

A transverse wave is described by the equation $ y = A \sin \left( 2 \pi \left( \frac{r}{\lambda} - \frac{t}{T} \right) \right) $. The maximum particle velocity is equal to four times the wave velocity if:

A piece of copper and another of germanium are cooled from room temperature to 100K. The resistance of

A particle of mass $m$ is moving in the potential
\[ V(x) = \begin{cases} V_0 + \frac{1}{2} m \omega_{0P}^2 x^2 & \quad \text{if } x > 0 \\ \infty & \quad \text{if } x \leq 0 \end{cases} \]
Figures P, Q, R, and S show different combinations of the values of $ \omega_0 $ and $ V_0 $.

In the x-y plane, a vector is given by
$\overrightarrow𝐹 (𝑥, 𝑦) = \frac{−𝑦𝑥̂ + 𝑥𝑦̂}{𝑥^ 2 + 𝑦^2} . $
The magnitude of the flux of $\overrightarrow∇ ×\overrightarrow 𝐹$ , through a circular loop of radius 2, centered at the origin, is:

Consider a thick biconvex lens (thickness t=4cm and refractive index n=1.5) whose magnitudes of the radii of curvature R1 and R2, of the first and second surfaces are 30cm and 20cm, respectively. Surface 2 is silvered to act as a mirror. A point object is placed at point A on the axis (OA= 60cm) as shown in the figure. If its image is formed at point Q, the distance d between O and Q is_____ cm. (Rounded off to two decimal places)

A region in the form of an equilateral triangle (in x-y plane) of height $ L $ has a uniform magnetic field $ \mathbf{B} $ pointing in the $ +z $-direction. A conducting loop PQR, in the form of an equilateral triangle of the same height $ L $, is placed in the x-y plane with its vertex $ P $ at $ x = 0 $ in the orientation shown in the figure. At $ t = 0 $, the loop starts entering the region of the magnetic field with a uniform velocity $ \mathbf{v} $ along the $ +x $-direction. The plane of the loop and its orientation remain unchanged throughout its motion.

region in the form of an equilateral triangleRead more on Sarthaks.com - https://www.sarthaks.com/3648677/region-in-the-form-of-an-equilateral-triangle-in-plane-of-height-has-uniform-magnetic-field

Which of the following graphs best depicts the variation of the induced emf ($ \mathcal{E} $) in the loop as a function of the distance ($ x $) starting from $ x = 0 $?

An infinitely long thin wire, having a uniform charge density per unit length of $5 \, \text{nC/m}$, is passing through a spherical shell of radius $1 \, \text{m}$, as shown in the figure. A $10 \, \text{nC}$ charge is distributed uniformly over the spherical shell. If the configuration of the charges remains static, the magnitude of the potential difference between points $P$ and $R$, in Volt, is ______. \[ \text{(Given: In SI units } \frac{1}{4\pi\epsilon_0} = 9 \times 10^9, \ln 2 = 0.7). \] Ignore the area pierced by the wire.

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The ratio of the wavelengths of the first and second Balmer lines of the hydrogen spectrum is:

A proton and an alpha particle are moving with kinetic energies of 4.5 MeV and 0.5 MeV respectively. The ratio of the de Broglie wavelengths of the proton and alpha particle is:

A magnetron valve is used to produce:

A coil having 0.64 mH inductance and 0.8 $\Omega$ resistance connected to a battery of 12 V. The energy stored in the magnetic field created by that coil is:

Relative permeability ($\mu_r$) of a sample is given by $1<\mu_r<1 + \epsilon$, where $\epsilon$ is a small positive number. Then the nature of the sample is:

In a Galvanometer, if the number of turns in the coil are doubled, then the electrical current sensitivity will be: