List of practice Questions

Find the net resistance of the network of resistors connected between \(A\) and \(B\), as shown in the figure.

Assertion (A) : If accelerated electrons are passed through a narrow slit, a diffraction pattern is observed. Reason (R) : Electrons behave as both particles and waves.

Assertion (A) : The mass of a nucleus is less than the sum of the masses of the constituent nucleons. Reason (R) : Energy is absorbed when the nucleons are bound together to form a nucleus.

Assertion (A) : In Bohr model of hydrogen atom, the energy levels are discrete and quantised. Reason (R) : In a hydrogen atom, the electrostatic force on the electron provides the necessary centripetal force to it to revolve around the nucleus.

In a photoelectric experiment, the emitter plate is irradiated with radiation of \(200\ \text{nm}\). The photocurrent becomes zero when the collector plate potential is \(-0.80\ \text{V}\). Calculate the work function (in eV) of the emitter.

A beam of light consisting of two wavelengths \(400\ \text{nm}\) and \(600\ \text{nm}\) is used to illuminate a single slit of width \(1\ \text{mm}\). Find the least distance of the point from the central maximum where the dark fringes due to both wavelengths coincide on the screen placed \(1.5\ \text{m}\) from the slit.

In a Young's double-slit experimental set-up with slit separation \(0.6\ \text{mm}\), a beam of light consisting of two wavelengths \(440\ \text{nm}\) and \(660\ \text{nm}\) is used to obtain an interference pattern on a screen kept \(1.5\ \text{m}\) in front of the slits. Find the least distance of the point from the central maximum where the bright fringes due to both the wavelengths coincide.

A wire of length \(L\) is bent round into (i) a square coil having \(N\) turns and (ii) a circular coil having \(N\) turns. The coil in both cases is free to turn about a vertical axis coinciding with the plane of the coil, in a uniform, horizontal magnetic field and carry the same currents. Find the ratio of the maximum value of the torque acting on the square coil to that on the circular coil.

The ‘distance of closest approach’ of an alpha-particle is \(d\) when it moves with a velocity \(v\) head-on towards the target nucleus. If the velocity of alpha particle is halved, the new ‘distance of closest approach’ will be –

A concave lens of focal length \(10\) cm is cut into two identical plano-concave lenses. The focal length of each lens will be

Four independent waves are expressed as \[ (i)\; y_1=A_1\sin\omega t, \] \[ (ii)\; y_2=A_2\sin 2\omega t, \] \[ (iii)\; y_3=A_3\cos\omega t, \] \[ (iv)\; y_4=A_4\sin\left(\omega t+\frac{\pi}{3}\right) \] The interference between two of these waves is possible in

Two heaters rated as \((P_1,V)\) and \((P_2,V)\) are connected in series across a dc source of \(V/2\) volt. The power consumed by the combination will be –

In an unbiased p-n junction, at equilibrium, which of the following statements is true ?

Assertion (A) : All atoms have a net magnetic moment. Reason (R) : A current loop does not always behave as a magnetic dipole.

A conducting wire connects two charged metallic spheres \(A\) and \(B\) of radii \(r_1\) and \(r_2\) respectively. The distance between the spheres is very large compared to their radii. The ratio of electric fields, \((E_A/E_B)\), at the surfaces of spheres \(A\) and \(B\) will be

A long straight wire of circular cross-section (radius \(a\)) carries a steady current \(I\). The current is uniformly distributed across this cross-section. The magnitude of the magnetic field produced at a point at a distance \(\dfrac{a}{2}\) from the axis of the wire will be

The shape of the interference fringes in Young's double-slit experiment, when the distance between the slit and the screen is very large as compared to the slit separation, is nearly

An electromagnetic wave passes from vacuum into a dielectric medium with relative electrical permittivity \(\dfrac{3}{2}\) and relative magnetic permeability \(\dfrac{8}{3}\). Then, its

In a series LCR circuit, the voltage across the resistor, capacitor and inductor is \(10\ \text{V}\) each. If the capacitor is short circuited, the voltage across the inductor will be

Electromagnetic waves used in a diagnostic tool in medicine have a wavelength range

A circular coil of \(100\) turns and radius \[ \left(\frac{10}{\pi}\right)\text{ cm} \] carrying current \(5.0\) A is suspended vertically in a uniform horizontal magnetic field of \(2.0\) T. The field makes an angle \(30^\circ\) with the normal to the coil. Calculate:
(I) the magnetic dipole moment of the coil, and
(II) the magnitude of the counter torque required to prevent the coil from turning.

Derive an expression for the force \(\vec F\) acting on a conductor of length \(L\) and area of cross-section \(A\) carrying current \(I\) and placed in a magnetic field \(\vec B\).

A part of a wire carrying \(2.0\) A current and bent at \(90^\circ\) at two points is placed in a region of uniform magnetic field \[ \vec B=-0.50\,\hat k\,T. \]

Calculate the magnitude of the net force acting on the wire.

A parallel beam of monochromatic light falls normally on a single slit of width \(a\) and a diffraction pattern is observed on a screen placed at distance \(D\) from the slit. Explain:
(I) the formation of maxima and minima in the diffraction pattern, and
(II) why the maxima go on becoming weaker and weaker with increasing order \(n\).

Write any two points of difference between interference pattern due to double-slit and diffraction pattern due to single-slit.