List of practice Questions

Draw a ray diagram to show the image formation by a compound microscope. Obtain the expression for the total magnification of the microscope when the final image is formed at infinity.
Show that the nuclear density is independent of mass number.
(a) Consider the so-called ‘D-T reaction’ (Deuterium-Tritium reaction).
In a thermonuclear fusion reactor, the following nuclear reaction occurs: \[ \ ^{2}_1 \text{H} + \ ^{3}_1 \text{H} \longrightarrow \ ^{4}_2 \text{He} + \ ^{1}_0 \text{n} + Q \] Find the amount of energy released in the reaction.
% Given data Given:
\( m\left(^{2}_1 \text{H}\right) = 2.014102 \, \text{u} \)
\( m\left(^{3}_1 \text{H}\right) = 3.016049 \, \text{u} \)
\( m\left(^{4}_2 \text{He}\right) = 4.002603 \, \text{u} \)
\( m\left(^{1}_0 \text{n}\right) = 1.008665 \, \text{u} \)
\( 1 \, \text{u} = 931 \, \text{MeV}/c^2 \)
How is the necessary force provided to an electron to keep it moving in a circular orbit according to Bohr model of hydrogen atom? Derive an expression for the total energy of an electron moving in an orbit of radius \( r \) in hydrogen atom. Give the significance of the negative sign in this expression.
State Lenz’s law. A rod MN of length \( L \) is rotated about an axis passing through its end M perpendicular to its length, with a constant angular velocity \( \omega \) in a uniform magnetic field \( \vec{B} \) parallel to the axis. Obtain an expression for emf induced between its ends.
Define ‘self-inductance’ of a coil. Derive an expression for self-inductance of a long solenoid of cross-sectional area \( A \) and length \( l \), having \( n \) turns per unit length.
Two cells of EMFs \( E_1 \) and \( E_2 \), and internal resistances \( r_1 \) and \( r_2 \), are connected in parallel. Derive an expression for the EMF and internal resistance of the equivalent cell.
A rectangular loop carries a current of 1 A. A straight long wire carrying 2 A current is kept near the loop in the same plane as shown in the figure.
rectangular loop carries a current of 1 A.
Find:
(i) the torque acting on the loop, and
(ii) the magnitude and direction of the net force on the loop.
In an n-type semiconductor, electron-hole combination is a continuous process at room temperature. Yet the electron concentration is always greater than the hole concentration in it. Explain.
Draw a ray diagram showing the image formation when a concave mirror produces a real, inverted, and magnified image of an object and hence obtain the mirror formula.
Name the electromagnetic wave used (i) in radar, (ii) in eye surgery, and (iii) as a diagnostic tool in medicine. Write their wavelength range also.
A laser beam of frequency \( 3.0 \times 10^{14} \) Hz produces average power of 9 mW. Find (i) the energy of a photon of the beam, and (ii) the number of photons emitted per second on an average by the source.
A point source of light in air is kept at a distance of 12 cm in front of a convex spherical surface of glass of refractive index 1.5 and radius of curvature 30 cm. Find the nature and position of the image formed.
Find the intensity at a point on the screen in Young’s double slit experiment, at which the interfering waves of intensity \( I_0 \) each, have a path difference of (i) \( \frac{\lambda}{3} \), and (ii) \( \frac{\lambda}{2} \).
Two statements are given one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.
Assertion (A): The binding energy per nucleon is practically constant for mass number in the range \( 30<A<170 \).
Reason (R): Nuclear forces between the nucleons for mass numbers in the range \( 30<A<170 \) are not short-range.
A right-angled isosceles glass prism ABC is kept in contact with an equilateral triangular prism DBC as shown in the figure. Both prisms are made of the same glass of refractive index 1.6. Trace the path of the ray MN incident normally on face AB as it passes through the combination.
right-angled isosceles glass prism
Find the equivalent resistance between points A and B for the network shown in the figure.
equivalent resistance between points A and B
Two statements are given one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.
Assertion (A): A hole is an apparent free particle with effective positive electronic charge.
Reason (R): A hole is not necessarily a vacancy left behind by an electron in the valence band.
Two statements are given one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.
Assertion (A): In a reflecting telescope, the image does not have chromatic aberration.
Reason (R): Chromatic aberration occurs only due to refraction of light through an optical medium.
Inside a nucleus, the nuclear forces between proton and proton, proton and neutron, neutron and neutron are \( F_{pp} \), \( F_{pn} \), and \( F_{nn} \) respectively. Then:
The work function of a material is 2.21 eV. Which of the following cannot produce photoelectrons from it?
Two statements are given one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.
Assertion (A): X-rays are produced when slow moving electrons are stopped by a metal target of high atomic number.
Reason (R): X-rays consist of low-energy photons.
The momentum (in kg·m/s) of a photon of frequency \( 6.0 \times 10^{14} \) Hz is:
Two coherent waves, each of intensity \( I_0 \), produce interference pattern on a screen. The average intensity of light on the screen is:
A galvanometer can be converted into an ammeter of desired range by connecting a: