List of top Questions asked in Maharashtra Board Class XII Exam

A bar magnet of mass 120 g in the form of a rectangular parallelepiped, has dimensions \( l = 40 \, \text{mm}, b = 100 \, \text{mm} \) and \( h = 80 \, \text{mm} \), with its dimension ‘h’ vertical, the magnet performs angular oscillations in the plane of the magnetic field with period \( \pi \) seconds. If the magnetic moment is 3.4 Am\(^2\), determine the influencing magnetic field.
Distinguish between free vibrations and forced vibrations (Two points).
Compare the rate of loss of heat from a metal sphere at 827°C with the rate of loss of heat from the same at 427°C, if the temperature of surrounding is 27°C.
An ideal mono-atomic gas is adiabatically compressed so that its final temperature is twice its initial temperature. Calculate the ratio of final pressure to its initial pressure.
Disintegration rate of a radio-active sample is \( 10^{10} \) per hour at 20 hours from the start. It reduces to \( 5 \times 10^9 \) per hour after 30 hours. Calculate the decay constant.
Derive laws of reflection of light using Huygens’ principle.
State postulates of Bohr’s atomic model.
Define and state unit and dimensions of:
(i) Magnetization
(ii) Magnetic susceptibility
Magnetization
Write the mathematical formula for Bohr magneton for an electron revolving in \( n \)th orbit.
Define coefficient of viscosity. State its formula and S.I. units.
Obtain an expression for magnetic induction of a toroid of \( N \) turns about an axis passing through its centre and perpendicular to its plane.
State and prove the principle of conservation of angular momentum.
Obtain an expression for equivalent capacitance of two capacitors \( C_1 \) and \( C_2 \) connected in series.
Explain why the equivalent inductance of two coils connected in parallel is less than the inductance of either of the coils.
How will you convert a moving coil galvanometer into an ammeter?
A 100 \(\Omega\) resistor is connected to a 220 V, 50 Hz supply.
Calculate:
(i) r.m.s. value of current
(ii) net power consumed over the full cycle
Answer the following questions:
What is the value of resistance for an ideal voltmeter?
What is the value of force on a closed circuit in a magnetic field?
What is the average value of alternating current over a complete cycle?
An electron is accelerated through a potential difference of 100 volts. Calculate the de-Broglie wavelength in nm.
If friction is made zero for a road, can a vehicle move safely on this road?
State the formula giving relation between electric field intensity and potential gradient.
Calculate the velocity of a particle performing S.H.M. after 1 second, if its displacement is given by \( x = 5 \sin\left(\frac{\pi t}{3}\right) \) m.
If a circular coil of 100 turns with a cross-sectional area of 1 m² is kept with its plane perpendicular to the magnetic field of 1 T, the magnetic flux linked with the coil will be ..........
If ‘θ’ represents the angle of contact made by a liquid which completely wets the surface of the container then ..........