31-10-2012, 03:32 PM
ELECTROMAGNETIC INDUCTION and AC CIRCUITS
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1.A magnet is allowed to fall through a metallic ring.During fall what will
be its acceleration? (Less than g)Can a choke coil can be used as a
step-up and step-down transformer.Justify
2.A magnetic flux linked with a coil,in webers, is given the equation 3
4t2+2t+15.The magnitude of induced emf at t = 2 Sec. is how much?
3.A radio frequency choke is air cored whereas an audio frequency
choke is iron-cored Give reason for this difference.
13. The above figure shows a horizontal solenoid connected to a
battery and a switch.A copper ring is placed on a frictionless track near
the solenoid, the axis of the ring being along the axis of the solenoid.
What will happen to the ring as the switch is closed? Justify your
answer.
14.A particle with charge ‘q’ and mass ‘ m’ is shot with kinetic energy K
into the region between two plates as shown in the figure. If the
magnetic field between the plates is B and as shown, how large must
B be if the particle isj to miss collision with the opposite plate?
A 40 Ohm resistor is connected across a 15 V variable frequency
electronic oscillator. Find the current through the resistor when the
frequency is (a) 100 Hz and (b) 100KHz. What is the current if the 40
Ohm resistor is replaced by a 2 mH inductor?
{ With resistor ,current is same both for 100 Hz and 100kHz. With
inductor , the current is 11.9 A and 11.9 mA respectively}
25.The current in a long solenoid of radius R and having n turns per unit
length is given by I = i0 VLQ&W $ FRLO KDYLQJ 1 WXUQV LV ZRXQG DURXQG LW
near the centre. Find (a) the induced emf in the coil and (b) the mutual
inductance between the solenoid and the coil.
^ D 0 i0Q1&52&RV&W E 0 nNR2 }
Give the condition for a current carrying loop not to rotate in a magnetic
field
26.A coil A is connected to voltmeter V and the other coil B to an
alternating current source D. If a large copper sheet CC is placed
between the two coils, how does the induced e.m.f in the coil A change
due to current in coil B?