List of top Physics Questions

Write any two features of nuclear forces.

Six point charges are kept \(60^\circ\) apart from each other on the circumference of a circle of radius \( R \) as shown in figure. The net electric field at the center of the circle is ___________. (\( \varepsilon_0 \) is permittivity of free space) 

The energy of an electron in an orbit in hydrogen atom is \( -3.4 \, \text{eV} \). Its angular momentum in the orbit will be:

Which of the following best represents the temperature versus heat supplied graph for water, in the range of \(-20^\circ\text{C}\) to \(120^\circ\text{C}\)? 

A small block of mass \(m\) slides down from the top of a frictionless inclined surface, while the inclined plane is moving towards left with constant acceleration \(a_0\). The angle between the inclined plane and ground is \(\theta\) and its base length is \(L\). Assuming that initially the small block is at the top of the inclined plane, the time it takes to reach the lowest point of the inclined plane is _______. 

An atom \({}_3^8 X\) is bombarded with electrons, neutrons and protons and in 10 sec, 10 electrons, 10 protons and 9 neutrons are absorbed. If final surface area is x% of initial area, find x : -
Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))
The time period of a simple harmonic oscillator is \[ T=2\pi\sqrt{\frac{m}{k}}. \] Measured value of mass \(m\) has an accuracy of \(10%\) and time for 50 oscillations of the spring is found to be \(60\,\text{s}\) using a watch of 2 s resolution. Percentage error in determination of spring constant \(k\) is:

Match List–I with List–II.

List–I                                       List–II
A. Coefficient of viscosity       I. [ M L^-1 T^-2 ]
B. Surface tension                  II. [ M L^-2 T^-2 ]
C. Pressure                             III. [ M L^0 T^-2 ]
D. Surface energy                  IV. [ M L^-1 T^-1 ]

Choose the correct answer from the options given below:

A Wheatstone bridge is initially at room temperature and all arms of the bridge have same value of resistances \[ (R_1=R_2=R_3=R_4). \] When \(R_3\) resistance is heated, its resistance value increases by \(10%\). The potential difference \((V_a-V_b)\) after \(R_3\) is heated is _______ V.

A nucleus has mass number \(\alpha\) and radius \(R_\alpha\). Another nucleus has mass number \(\beta\) and radius \(R_\beta\). If \(\beta=8\alpha\), then \(R_\alpha/R_\beta\) is:
For a transparent prism, if the angle of minimum deviation is equal to its refracting angle, the refractive index \(n\) of the prism satisfies:
A particle starts moving from time \(t=0\) and its coordinate is given as \[ x(t)=4t^3-3t. \] Consider the following statements:
[A.] The particle returns to its original position (origin) \(0.866\) units later.
[B.] The particle is \(1\) unit away from origin at its turning point.
[C.] Acceleration of the particle is non-negative.
[D.] The particle is \(0.5\) units away from origin at its turning point.
[E.] The particle never turns back as acceleration is non-negative.
Choose the correct answer from the options given below:
Number of photons of equal energy emitted per second by a 6 mW laser source
operating at wavelength 663 nm is _______.

(Given: h = 6.63 × 10^-34 J·s and c = 3 × 10^8 m/s)
The mean free path of a molecule of diameter \(5\times10^{-10}\,\text{m}\) at temperature \(41^\circ\text{C}\) and pressure \(1.38\times10^5\,\text{Pa}\) is given as _______ m. (Given \(k_B=1.38\times10^{-23}\,\text{J/K}\))

A biconvex lens is formed by using two plano-convex lenses as shown in the figure. The refractive index and radius of curvature of surfaces are also mentioned. When an object is placed on the left side of the lens at a distance of \(30\,\text{cm}\), the magnification of the image will be:

In an experiment, a set of readings are obtained as follows: \[ 1.24~\text{mm},\ 1.25~\text{mm},\ 1.23~\text{mm},\ 1.21~\text{mm}. \] The expected least count of the instrument used in recording these readings is _______ mm.
The speed of a longitudinal wave in a metallic bar is \(400\,\text{m/s}\). If the density and Young’s modulus of the bar material increase by \(0.5%\) and \(1%\) respectively, then the speed of the wave is changed approximately to _______ m/s.
When the position vector \[ \vec r = x\hat{i}+y\hat{j}+z\hat{k} \] changes sign as \(\vec r \rightarrow -\vec r\), which one of the following vectors will {not flip under sign change?}
An inductor stores \(16\,\text{J}\) of magnetic field energy and dissipates \(32\,\text{W}\) of thermal energy due to its resistance when an alternating current of \(2\,\text{A}\) (rms) and frequency \(50\,\text{Hz}\) flows through it. The ratio of inductive reactance to resistance is _______. \((\pi=3.14)\) Given: \[ U=16\,\text{J},\quad P=32\,\text{W},\quad I=2\,\text{A},\quad f=50\,\text{Hz} \]
A long cylindrical conductor with large cross section carries an electric current distributed uniformly over its cross-section. Magnetic field due to this current is:
[A.] maximum at either end of the conductor
[B.] maximum at the axis of the conductor and minimum at the midpoint
[C.] minimum at the surface of the conductor
[D.] minimum at the axis of the conductor
[E.] same at all points in the cross-section of the conductor
Choose the correct answer from the options given below:
Identify the correct statements:
[A.] Electrostatic field lines form closed loops.
[B.] The electric field lines point radially outward when charge is greater than zero.
[C.] The Gauss’s Law is valid only for inverse-square force.
[D.] The work done in moving a charged particle in a static electric field around a closed path is zero.
[E.] The motion of a particle under Coulomb’s force must take place in a plane.
Choose the correct answer from the options given below:
Which one of the following is not a measurable quantity?
A flywheel having mass \(3\,\text{kg}\) and radius \(5\,\text{m}\) is free to rotate about a horizontal axis. A string having negligible mass is wound around the wheel and the loose end of the string is connected to a \(3\,\text{kg}\) mass. The mass is kept initially and released. Kinetic energy of the flywheel when the mass descends by \(3\,\text{m}\) is _______ J. \((g=10\,\text{m s}^{-2})\) Given: \[ M = 3\,\text{kg}, \quad R = 5\,\text{m}, \quad m = 3\,\text{kg}, \quad h = 3\,\text{m}, \quad g = 10\,\text{m s}^{-2} \]

As shown in the figure, a spring is kept in a stretched position with some extension by holding the masses \(1\,\text{kg}\) and \(0.2\,\text{kg}\) with a separation more than spring natural length and then released. Assuming the horizontal surface to be frictionless, the angular frequency (in SI unit) of the system is _______. (Given \(k=150\,\text{N/m}\))