Maharashtra Board Class 12 Physics Question Paper 2023 with Answer Key pdf is available for download here. The question paper was divided into two sections - Section A for objective questions and Section B for subjective questions.
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Select and write the correct answers for the following multiple choice type of questions:
% Question Text
(i) If ‘n’ is the number of molecules per unit volume and ‘d’ is the diameter of the molecules, the mean free path ‘\(\lambda\) of molecules is
The LED emits visible light when its ...........
Soft iron is used to make the core of transformer because of its ...........
If the maximum kinetic energy of emitted electrons in photoelectric effect is 2eV, the stopping potential will be ............
The radius of eighth orbit of electron in H-atom will be more than that of fourth orbit by a factor of ........
Answer the following questions:
(i) What is the value of resistance for an ideal voltmeter?
(ii) What is the value of force on a closed circuit in a magnetic field?
(iii) What is the average value of alternating current over a complete cycle?
(iv) An electron is accelerated through a potential difference of 100 volts. Calculate the de-Broglie wavelength in nm.
(v) If friction is made zero for a road, can a vehicle move safely on this road?
(vi) State the formula giving relation between electric field intensity and potential gradient.
(vii) 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.
(viii) 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
A bar magnet of mass 120 g in the form of a rectangular parallelepiped, has dimensions \( l = 40 \, mm, b = 100 \, mm \) and \( h = 80 \, mm \), 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
(i) Magnetization
With neat labelled circuit diagram, describe an experiment to study the characteristics of the photoelectric effect.
Explain the use of potentiometer to determine the internal resistance of a cell.
Explain the working of n-p-n transistor in common base configuration.
State the differential equation of linear S.H.M. Hence, obtain expression for:
[(i)] Acceleration
[(ii)] Velocity
Correct Answer:
The differential equation of linear simple harmonic motion (S.H.M.) is \( m \frac{d^2x}{dt^2} = -kx \). From this, we can derive the expressions for acceleration and velocity.
Two tuning forks of frequencies 320 Hz and 340 Hz are sounded together to produce sound waves. The velocity of sound in air is 326.4 m/s. Calculate the difference in wavelengths of these waves.
In a biprism experiment, the fringes are observed in the focal plane of the eye-piece at a distance of 1.2 m from the slit. The distance between the central bright band and the 20th bright band is 0.4 cm. When a convex lens is placed between the biprism and the eye-piece, 90 cm from the eye-piece, the distance between the two virtual magnified images is found to be 0.9 cm. Determine the wavelength of light used.
Calculate the current flowing through two long parallel wires carrying equal currents and separated by a distance of 1.35 cm, experiencing a force per unit length of \( 4.76 \times 10^{-2} \, N/m \).
An alternating voltage given by \( e = 140 \sin (314.2 t) \) is connected across a pure resistor of 50 \(\Omega\).
Calculate:
[(i)] the frequency of the source
[(ii)] the r.m.s current through the resistor
An electric dipole consists of two opposite charges each of magnitude 1 µC, separated by 2 cm. The dipole is placed in an external electric field of \( 10^5 \, N/C \).
Calculate the:
[(i)] maximum torque experienced by the dipole
[(ii)] work done by the external field to turn the dipole through 180°
On the basis of kinetic theory of gases, obtain an expression for pressure exerted by gas molecules enclosed in a container on its walls.
(i) Derive an expression for energy stored in the magnetic field in terms of induced current.
(i) Derive an expression for the work done during an isothermal process.
(i) Obtain the relation between surface energy and surface tension.
Derive expressions for linear velocity at lowest position, mid-way position, and the top-most position for a particle revolving in a vertical circle, if it has to just complete circular motion without string slackening at the top.
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