List of practice Questions

Write any two features of nuclear forces.

Assertion (A) : Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion. Reason (R) : For heavy nuclei, binding energy per nucleon increases with increasing \(Z\) while for light nuclei, it decreases with increasing \(Z\).

Assertion (A) : Photoelectric effect is a spontaneous phenomenon. Reason (R) : According to the wave picture of radiation, an electron would take hours/days to absorb sufficient energy to overcome the work function and come out from a metal surface.

An electric iron rated \(2.2\,\text{kW},\,220\,\text{V}\) is operated at \(110\,\text{V}\) supply. Find: (i) its resistance, and (ii) heat produced by it in \(10\) minutes.

A current of \(4.0\,\text{A}\) flows through a wire of length \(1\,\text{m}\) and cross-sectional area \(1.0\,\text{mm}^2\), when a potential difference of \(2\,\text{V}\) is applied across its ends. Calculate the resistivity of the material of the wire.

A plane circular coil is rotated about its vertical diameter with a constant angular speed \(\omega\) in a uniform horizontal magnetic field. Initially the plane of the coil is parallel to the magnetic field. Draw the plot showing the variation of magnetic flux \(\phi\) linked with the coil as a function of \(\omega t\), where \(t\) represents the time elapsed.

A plane circular coil is rotated about its vertical diameter with a constant angular speed \(\omega\) in a uniform horizontal magnetic field. Initially the plane of the coil is parallel to the magnetic field. Draw the plot showing the variation of induced emf \(e\) in the coil as a function of \(\omega t\), where \(t\) represents the time elapsed.

A tank is filled with a liquid to a height of \(12.5\,\text{m}\). The apparent depth of a needle lying at the bottom of the tank is measured to be \(9.0\,\text{m}\). Calculate the speed of light in the liquid.

The radius of a nucleus of mass number 125 is

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

A good diode checked by a multimeter should indicate:

The rms and the average value of an ac voltage \[ V=V_0\sin\omega t \] over a cycle respectively will be:

Assertion (A) : Induced emf produced in a coil will be more when the magnetic flux linked with the coil is more. Reason (R) : Induced emf produced is directly proportional to the magnetic flux.

Assertion (A) : In Young's double-slit experiment, the fringe width for dark and bright fringes is the same. Reason (R) : Fringe width is given by \[ \beta=\frac{\lambda D}{d}, \] where symbols have their usual meanings.

The figure represents the variation of the electric potential \(V\) at a point in a region of space as a function of its position along the \(x\)-axis. A charged particle will experience the maximum force at:

Four long straight thin wires are held vertically at the corners \(A\), \(B\), \(C\) and \(D\) of a square of side \(a\), kept on a table and carry equal current \(I\). The wire at \(A\) carries current in upward direction whereas the current in the remaining wires flows in downward direction. The net magnetic field at the centre of the square will have the magnitude:

The magnetic flux through a loop placed in a magnetic field can be changed by changing:

Which of the following statements is not true for electric energy in ac form compared to that in dc form?

The magnetic field in a plane electromagnetic wave travelling in glass \((n = 1.5)\) is given by \[ B_y=(2\times10^{-7}\,\text{T})\sin(\alpha x+1.5\times10^{11}t) \] where \(x\) is in metres and \(t\) is in seconds. The value of \(\alpha\) is:

Light of which of the following colours will have the maximum energy in a photon associated with it?

Nuclides with the same number of neutrons are called:

State Lenz’s law and explain that it follows the law of conservation of energy.

Write the dimensional formula for self-inductance.
The current in a coil changes from 8·0 A to 2·0 A in 0·6 s. If an average emf induced in the coil is 50 V, calculate the self-inductance of the coil.

A point object is kept in front of a convex spherical surface of radius of curvature $R$. Draw the ray diagram to show the formation of image and derive the relation between the object and image distance ($u$ and $v$) in terms of refractive index $n$ of the medium and $R$.

A convex lens of focal length of $20\text{ cm}$ is used to form the image of an object placed $30\text{ cm}$ away from the lens. Find the position and nature of the image formed.