Download 10 mst perpendicular to a magnetic field of induction 1 Wb na2

PAVITRA GUPTA 9312281591
PAVITRA GUPTA 9312281591
EMI (Numericals)
Q.1
Q.2
Q.3
Q.4
Q.5
Q.6
Q.7
Q.8
Q.9
Q.10
Q.11
Q.12
Q.13
Q.14
Q.15
Q.16
Q.17
Q.18
Q.19
Q.20
Q.21
A wire of length 0.1 m moves with a speed of 10 m/s perpendicular to a magnetic field of induction
1 Wb/m2. Calculate induced emf.
[1V]
A jet plane is travelling towards west at a speed of 1800 km/h. What is the voltage difference developed
between the ends of the wing having a span of 25 m, if the Earth’s magnetic field at the location has a
magnitude of 5 × 10–4 T and the dip angle is 30°.
[3.1 V]
A wire 88 cm long bent into a circular loop is placed perpendicular to the magnetic field of flux density
2.5 W/m2. Within 0.5 sec, the loop is changed into a square of each side 22 cm and flux density is
increased to 3.0 Wb/m2. Calculate the value of emf induced.
[0.018 V]
A circular coil of radius 10 cm, 500 turns and resistance 2 Ω is placed with its plane perpendicular to the
horizontal component of the earth’s magnetic field. It is rotated about its vertical diameter through 180°
in 0.25 s. Estimate the magnitudes of the emf and current induced in the coil. Horizontal component of
the earth’s magnetic field at the place is 3.0 × 10–5 T.
[3.8 × 10–3 V, 1.9 × 10–3 A]
A wheel with 10 metallic spokes each 0.5 m long is rotated with a speed of 120 rev/min in a plane
normal to the horizontal component of earth’s magnetic field HE at a place. If HE = 0.4 G at the place,
what is the induced emf between the axle and the rim of the wheel?
[6.28 × 10–5 V]
A horizontal straight wire 10 m long extending from east to west is falling with a speed of 5.0 m s–1, at
right angles to the horizontal component of the earth’s magnetic field, 0.30 × 10–4 Wb m–2.
(a) What is the instantaneous value of the emf induced in the wire? (b) What is the direction of the emf?
(c) Which end of the wire is at the higher electrical potential?
[1.5 × 10–3 V, West to East, Eastern]
A pair of adjacent coils has a mutual inductance of 1.5 H. If the current in one coil changes from 0 A to
20 A in 0.5 s, what is the change of flux linkage with the other coil?
[30 Wb]
An average induced emf of 0.20 V appears in a coil when the current in it is changed from 5 A in one
direction to 5 A in the opposite direction in 0.20 s. Find the self inductance of the coil?
[4 x 10-3 H]
Magnetic flux when a current self inductance of 5 microweber is linked with a coil of 1 mA flows
through it. What is self inductance of the coil?
[5 mH]
A solenoid of length 20 cm, area of cross-section 4 cm2 and having 4000 turns is placed inside another
solenoid of 2000 turns having a cross sectional area 8 cm2 and length 10 cm. Find the mutual inductance
between the solenoids.
[2 x 10-2H]
If self induction of an air core solenoid increases from 0.04 mH to 16 mH on introducing an iron core
into it, what is relative magnetic permeability of the core?
[400]
A coil of wire of certain radius has 600 turns and a self inductance of 108 mH. What will be self
inductance similar coil which has 500 turns?
[75mH]
What is the power dissipation in a.c. circuit, if the voltage and current are given by:
V = 300 sin(ωt + /2) and I = 5 sinωt
[zero]
The electric mains in a house are marked 220 V, 50Hz. Write down the equation for instantaneous
voltage.
[311 sin 100t]
The instantaneous current from an a.c. source is given by I = 5 sin 3l4 t. What is the frequency and rms
value of the current?
[50 Hz, 3.54A]
If the effective current in a 50 cycle a.c. circuit is 5 A, what is the peak value of current? What is the
current 1/600 sec. after it was zero?
[7.07A, 3.535A]
Find the maximum value of current when inductance of 2 H is connected to 150 V, 50 cycles supply.
The output voltage of an ideal transformer, connected to a 240 V a.c. mains is 24 V. When this
transformer is used to light a bulb with rating 24 V, 24 W, calculate the current in the primary coil of
the circuit.
Calculate the current drawn by the primary of a transformer, which steps down 200 V to 20 V to operate
a device of resistance 20 Ω. Assume the efficiency of the transformer to be 80 %.
An alternating current of 1.5 mA r.m.s. and angular frequency 100 radian/s flows through a 10 kΩ
resistor and a 0.50 F capacitor in series. Calculate the value of r.m.s. voltage across the capacitor and
the impedance of the circuit.
[30 V, 22.4 kΩ]
A series LCR circuit is connected to a variable frequency 220 V source with L = 4.0 H, C = l00 F and
R = 40Ω (i) Calculate the resonant frequency of the circuit. (ii) Obtain the impedance of the circuit and
the amplitude of the current at resonating frequency. (iii) Determine r.m.s. potential drop across L.
PAVITRA GUPTA 9312281591
Page 1 of 2
PAVITRA GUPTA 9312281591
PAVITRA GUPTA 9312281591
Q.22
Q.23
Q.24
Q.25
Q.26
Q.27
Q.28
Q.29
PAVITRA GUPTA 9312281591
What is the value of current in the a.c. circuit containing R = 10 Ω, C = 50 F in series across 200 V,
50 Hz a.c. source?
[3.1 A]
A capacitor, resistor of 5 Ω, and an inductor of 50 mH are in series with an a.c. source marked 100 V,
50 Hz. It is found that voltage is in phase with the current. Calculate the capacitance and the impedance
of the circuit.
An 80 V, 800W heater is to be operated on a 100 V, 50 Hz supply. Calculate the inductance of the
choke required.
[1.9 x 10-2 H]
An a.c. generator consists of a coil of 50 turns and area 2.5 m2 rotating at angular speed of 60 radian/s in
a uniform magnetic field of 0.30 T. The resistance of the circuit including that of the coil is 500 Ω.
What is the maximum current drawn from the generator?
An LC circuit contains a 20 mH inductor and a 50F capacitor with an initial charge of 10 mC. The
resistance of the circuit is negligible. Let the instant when the circuit is closed be t = 0.
(a) What is the total energy stored initially?
(b) What is the natural frequency of the circuit?
[1.0 J, 159 Hz]
What is the value of effective current of an a.c. having peak value of 5 A. What will be the reading for it
by (i) a.c. ammeter (ii) ordinary moving coil ammeter?
The magnetic flux through a coil perpendicular to its plane is varying according to
 = ( 5 t2 + 10 t + 5 ) mWb. Calculate emf induced at t = 5 s.
[0.06 V]
A choke coil and a resistance are connected in series in a.c. circuit. A potential of 130 V is applied. If
p.d. across resistance is 50 V, what would be p.d. across choke coil?
[120 V]
PAVITRA GUPTA 9312281591
Page 2 of 2
PAVITRA GUPTA 9312281591