HSC Science (Computer Science) 12th Standard Board Exam - Maharashtra State Board Question Bank Solutions for Physics

Answer in brief.

What does the hysteresis loop represent?

State the law of equipartition of energy and hence calculate the molar specific heat of mono-atomic and di-atomic gases at constant volume and constant pressure.

In a Faraday disc dynamo, a metal disc of radius R rotates with an angular velocity ω about an axis perpendicular to the plane of the disc and passing through its center. The disc is placed in a magnetic field B acting perpendicular to the plane of the disc. Determine the induced emf between the rim and the axis of the disc.

A horizontal wire 20 m long extending from east to west is falling with a velocity of 10 m/s normal to the Earth’s magnetic field of 0.5 × 10⁻⁴ T. What is the value of induced emf in the wire?

A stiff semi-circular wire of radius R is rotated in a uniform magnetic field B about an axis passing through its ends. If the frequency of rotation of wire is f, calculate the amplitude of alternating emf induced in the wire.

Show that in an AC circuit containing a pure inductor, the voltage is ahead of current by π/2 in phase.

Which property of light does not change when it travels from one medium to another?

What is the difference between a nuclear reactor and a nuclear bomb?

The half-life of \[\ce{_38^90Sr}\] is 28 years. Determine the disintegration rate of its 5 mg sample.

A needle of a sewing machine moves along a path of amplitude 4 cm with a frequency of 5 Hz. Find its acceleration `(1/30)` s after it has crossed the mean position.

Potential energy of a particle performing linear S.H.M. is 0.1 π²x² joule. If the mass of the particle is 20 g, find the frequency of S.H.M.

At what distance from the mean position is the kinetic energy of a particle performing S.H.M. of amplitude 8 cm, three times its potential energy?

The dipole moment of a water molecule is 6.3 x 10^-30 c·m. A sample of water contains 10²¹ molecules, whose dipole moments are all oriented in an electric field of strength 2.5 x 10⁵N/C. Calculate the work to be done to rotate the dipoles from their initial orientation θ₁ = 0° to one in which all the dipoles are perpendicular to the field, θ₂ = 90°.

A search coil having 2000 turns with area 1.5 cm² is placed in a magnetic field of 0.60 T. The coil is moved rapidly out of the field in a time of 0.2 s. Calculate the induced emf in the search coil.

Calculate the induced emf between the ends of an axle of a railway carriage 1.75 m long traveling on level ground with a uniform velocity of 50 kmph. The vertical component of Earth's magnetic field (B_v) is 5 × 10^-5 T. 

In nuclear reactors, neutrons travel with energies of 5 × 10^-21J. Find their speed and wavelength.

A string of length ℓ fixed at one end carries a mass m at the other. The string makes 2/π revolutions/sec around the vertical axis through the fixed end. The tension in the string is ______.

State and explain the theorem of parallel axes.

Show that the average energy of the molecules of a gas is directly proportional to the absolute temperature of the gas. 

Determine the molecular kinetic energy (i) per mole (ii) per gram (iii) per molecule of nitrogen molecules at 227°C, R = 8.310 J mole^-1 K^-1,No = 6.03 x 10²⁶ moleculesKmole^-1. Molecular weight of nitrogen = 28.