HSC Science (Electronics) १२ वीं कक्षा - Maharashtra State Board Question Bank Solutions for Physics

Prove that an ideal capacitor in an AC circuit does not dissipate power

(a) An emf e = e₀ sin ωt applied to a series L - C - R circuit derives a current I = I₀sinωt in the circuit. Deduce the expression for the average power dissipated in the circuit.
(b) For circuits used for transporting electric power, a low power factor implies large power loss in transmission. Explain.

An AC source generating a voltage e = e₀sinωt is connected to a capacitor of capacitance C. Find the expression for the current i flowing through it. Plot a graph of e and i versus ωt.

A light bulb is rated 100W for 220 V AC supply of 50 Hz. Calculate

1. resistance of the bulb.
2. the rms current through the bulb

An AC circuit consists of only an inductor of inductance 2 H. If the current is represented by a sine wave of amplitude 0.25 A and frequency 60 Hz, calculate the effective potential difference across the inductor. (π = 3.142)

Alternating emf of e = 220 sin 100 πt is applied to a circuit containing an inductance of (1/π) henry. Write an equation for instantaneous current through the circuit. What will be the reading of the AC galvanometer connected in the circuit?

A 25 μF capacitor, a 0.10 H inductor, and a 25Ω resistor are connected in series with an AC source whose emf is given by e = 310 sin 314 t (volt). What is the frequency, reactance, impedance, current, and phase angle of the circuit?

A 100 μF capacitor is charged with a 50 V source supply. Then source supply is removed and the capacitor is connected across an inductance, as a result of which 5A current flows through the inductance. Calculate the value of the inductance.

Answer in brief.

What sets the limits on the efficiency of a heat engine?

Draw a p-V diagram and explain the concept of positive and negative work. Give one example each.

The figure shows the V-T diagram for one cycle of a hypothetical heat engine which uses the ideal gas. Draw the p-V diagram diagram of the system.

Draw graphs of displacement, velocity, and acceleration against phase angle, for a particle performing linear S.H.M. from

1. the mean position
2. the positive extreme position. 

Deduce your conclusions from the graph.

Two sound waves travel at a speed of 330 m/s. If their frequencies are also identical and are equal to 540 Hz, what will be the phase difference between the waves at points 3.5 m from one source and 3 m from the other if the sources are in phase?

A set of 8 tuning forks is arranged in a series of increasing order of frequencies. Each fork gives 4 beats per second with the next one and the frequency of last fork is twice that of the first. Calculate the frequencies of the first and the last fork.

Answer in brief:

If a copper disc swings between the poles of a magnet, the pendulum comes to rest very quickly. Explain the reason. What happens to the mechanical energy of the pendulum?

The angular momentum of a system of particles is conserved ______ 

Obtain an expression for the angular momentum of a body rotating with uniform angular velocity.

Show the graphical representation of radiant power of a black body per unit range of wavelength as a function of wavelength.

Draw a neat labeled diagram of Ferry’s black body. 

Explain the construction and working of Ferry’s black body.