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Electromagnetic Induction and Alternating Current - Question Bank |
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Written by PhysicsMaster
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Sunday, 20 September 2009 07:10 |
Electromagnetic Induction and Alternating Current
(1) Name the conservation law on which Lenz’s law is tested .
(2) Give the dimensional formula for (i) f (ii) L (iii) B
(3) Discuss the role of self induction in an electrical circuit.
(4) How non inductive winding is done in resistance box?
(5) Find the mutual inductance between two plane coils –
(i) When they lie on same plane (ii) When they lie mutually perpendicular
(6) A coil of area, having N number of turns is rotated in a uniform magnetic field withuniform angular velocity.
(7) Show mathematically that in a pure inductive circuit Voltage leads the current by π /2 phase.
(8)Deduce an expression for each of inductive and capacitive reactance.
(9)Write the expression for average power in an A.C. circuit. Thus show that no power is dissipated across an inductor and a capacitor.
(10)What are the various factors on which mutual inductance of two coils depend on .
(11) Find the energy stored in an inductor – When a current passes through it. Then find the energy stored per unit volume of a magnetic field.
(12) Show that displacement current in a capacitor is same as conduction current.
(13) A closed loop cuts through a uniform magnetic field. Find the expression for current induced and the force required to carry the coil with constant velocity.
(14) What is eddy current? How eddy current could be minimized?
(15) What are different losses in a transformer?
(16) What is resonance in an LCR circuit .
(17) Show that in an LC circuit – the sum of energies stored in a capacitor and an inductor is constant in time.
UNDERSTANDING BASED QUESTIONS:
(1) Distinguish between ‘average value’ and ‘rms’ value of an alternating current.
(2) Why a bar magnet falling freely under gravity through a ring – falls with a smaller acceleration ?
(3) How can you explain the production of emf in a moving rod through a uniform magnetic field. what is the necessary condition for the flow of induced current ?
(4) Explain the statement “Current will never set or die off in an ideal inductor”.
(5) Why a d.c. can’t be transformed by a transformer?
(6) An electric bulb could be used in both a.c. and d.c. but a fan cann’t be used in d.c.
(7) How the mutual inductance of two coils change with the orientation of the coils ?
(8) A coil is taken away from a magnet i) rapidly ii) slowly over same distance . In
which case more work is performed and why?
(9) How does the self inductance of an air core coil change when
i) No. of turn in the coil is doubled ii) An iron bar is introduced
iii)Length of the coil is halved - by keeping no. of turns same .
(10) Why a capacitor acts as a short circuit at high frequency – but as an open circuit for d.c.
(11) A small resistor is connected across a motor – why ?
(12) In an L-C circuit the charge on the capacitor is sometimes zero , even though there is a current in the circuit . Why?
(13) Under what condition power consumed in a series L-C-R circuit is maximum.
(14) How can you say that Lenz’s law follows the principle of conservation of energy .
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