HSC Science (Electronics) 12th Standard Board Exam - Maharashtra State Board Question Bank Solutions

A circular coil of 250 turns and diameter 18 cm carries a current of 12A. What is the magnitude of magnetic moment associated with the coil?

State an expression for K. E. (kinetic energy) and P. E. (potential energy) at displacement ‘x’ for a particle performing linear S.H. M. Represent them graphically. Find the displacement at which K. E. is equal to P. E.

Let n₁ and n₂ be the two slightly different frequencies of two sound waves. The time interval between waxing and immediate next waning is ______.

(A) `1/(n_1-n_2)`

(B) `2/(n_1-n_2)`

(C) `(n_1-n_2)/2`

(D) `1/(2(n_1-n_2))`  

Draw a neat labelled diagram for Davisson and Germer experiment, for diffraction of electron wave.

An ideal voltmeter has _______.

(A) low resistance

(b) high resistance

(C) infinite resistance

(D) zero resistance

Describe, with the help of a circuit diagram, the working of Zener diode as a voltage regulator.

Stretching of a rubber band results in _______.

(A) no change in potential energy.

(B) zero value of potential energy.

(C) increase in potential energy.

(D) decrease in potential energy.

A body cools at the rate of 0.5°C / minute when it is 25° C above the surroundings. Calculate the rate of cooling when it is 15°C above the same surroundings.

Prove the law of conservation of energy for a particle performing simple harmonic motion.Hence graphically show the variation of kinetic energy and potential energy w. r. t. instantaneous displacement.

Explain how moving coil galvanometer is converted into a voltmeter. Derive the necessary formula.

A rectangular coil of a moving coil galvanometer contains 100 turns, each having area
15 cm². It is suspended in the radial magnetic field 0.03 T. The twist constant of suspension
fibre is 15 x 10^-10 N-m/degree. Calculate the sensitivity of the moving coil galvanometer.

Within the elastic limit, find the work done by a stretching force on a wire.

A set of 12 tuning forks is arranged in order of increasing frequencies. Each fork produces Y beats per second with the previous one. The last is an octave of the first. The fifth fork
has a frequency of 90 Hz. Find Y and frequency of the first and the last tuning forks.

If the Earth completely loses its gravity, then for any body _______.

(A) both mass and weight become zero.
(B) neither mass nor weight become zero.
(C) weight becomes zero but not the mass.
(D) mass becomes zero but not the weight.

Draw a neat, labeled diagram showing different layers of the Earth’s atmosphere.

A sonometer wire vibrates with three nodes and two antinodes, the corresponding mode of vibration is ...................

a) First overtone

b) Second overtone

c) Third overtane

d) Fourth overtone

The fraction of the total current passing through the galvanometer is ............ .

a) `S/(S+G)`

b) `G/(S+G)`

c) `(S+G)/G`

d) `(S+G)/S`

A moving coil galvanometer has a resistance of 25Ω and gives a full scale deflection for a current of 10mA. How will you convert it into a voltmeter having range 0 - 100 V?

The kinetic energy of nitrogen per unit mass at 300 K is 2.5 × 106 J/kg. Find the kinetic energy of 4 kg oxygen at 600 K. (Molecular weight of nitrogen = 28, Molecular weight of oxygen = 32)

A galvanometer has a resistance of 16Ω. It shows full scale deflection, when a current of 20 mA is passed through it. The only shunt resistance available is 0.06  which is not appropriate to convert a galvanometer into an ammeter. How much resistance should be connected in series with the coil of galvanometer, so that the range of ammeter is 8 A?