HSC Science (Electronics) 12th Standard Board Exam - Maharashtra State Board Important Questions

An alternating emf of 230V, 50Hz is connected across a pure ohmic resistance of 50Ω. Find (1) the current (2) equations for instantaneous values of current and voltage.

Obtain the expression for the applied emf and the effective resistance of the circuit when alternating emf is applied to an LR circuit.

Obtain the expression for the applied emf and the effective resistance of the circuit when alternating emf is applied to a CR circuit.

A 100 Ω resistor is connected to a 220 V, 50 Hz ac supply.

1. What is the rms value of current in the circuit?
2. What is the net power consumed over a full cycle?

Define Inductive reactance.

Define Capacitive reactance.

Define Impedance.

What is the average value of alternating current over a complete cycle?

An alternating voltage is given by e = 8sin628.4t. Find

1. peak value of e.m.f.
2. frequency or e.m.f.
3. instantaneous value of e.m.f. at time t = 10. ms

Draw a neat labelled diagram for the construction of 'cyclotron'

The combined resistance of a galvanometer of resistance 500Ω and its shunt is 21Ω. Calculate the value of shunt.

A rectangular coil of a moving coil galvanometer contains 50 turns each having area 12 cm2 . It is suspended in radial magnetic field 0.025 Wb/m² by a fibre of twist constant 15 x10^-10 Nm/degree. Calculate the sensitivity of the moving coil galvanometer.

Show that the current flowing through a moving coil galvanometer is directly proportional to the angle of deflection of coil.

In a cyclotron, magnetic field of 3·5Wb/m2 is used to accelerate protons. What should be the time interval in which the electric field between the Dees be reversed?
(Mass of proton = 1· 67 x 10^-27Kg, Charge on proton =1·6x10^-19c).

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?

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

If a watch-glass containing a small quantity of water is placed on two dissimilar magnetic poles, then water ______.

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.