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Two coupled coils with L1 = 0.5 H and L2 = 4.0 H have a co-efficient of coupling 0.8. Find maximum value of the inductance EMF in the coil 2 if a current of i1 = 20 sin 314t A is passed in coil 1.
  • a)
    22.6 V
  • b)
    444 V
  • c)
    7.1 kV
  • d)
    355 V
Correct answer is option 'C'. Can you explain this answer?
Most Upvoted Answer
Two coupled coils with L1 = 0.5 H and L2 = 4.0 H have a co-efficient o...
Concept :
Self-inductance is the property of the current-carrying coil that resists or opposes the change of current flowing through it. This occurs mainly due to the self-induced emf produced in the coil itself. In simple terms, we can also say that self-inductance is a phenomenon where there is the induction of a voltage in a current-carrying wire.
Self-inductance, usually just called inductance, L is the ratio between the induced voltage and the rate of change of the current
V1(t) = L (di1/dt)
Mutual Inductance between the two coils is defined as the property of the coil due to which it opposes the change of current in the other coil, or you can say in the neighboring coil. When the current in the neighboring coil changes, the flux sets up in the coil and, because of this, changing flux emf is induced in the coil called Mutually Induced emf and, the phenomenon is known as Mutual Inductance.
V2(t) = M (di1/dt)
Coefficient of Coupling :


The amount of coupling between the inductively coupled coils is expressed in terms of the coefficient of coupling, which is defined as

where M = mutual inductance between the coils
L1 = self-inductance of the first coil, and
L2 = self-inductance of the second coil
  • The coefficient of coupling is always less than unity and has a maximum value of 1 (or 100%).
  • This case, for which K = 1, is called perfect coupling when the entire flux of one coil links the other.
  • The greater the coefficient of coupling between the two coils, the greater the mutual inductance between them, and vice-versa.
Calculations :
Given 
L1 = 0.5 H
L2 = 4 H
K = 0.8
I = 20 sin 314t
The induced emf in coil 2 due to current in coil 1 is given by
V2 = M (di1 / dt)

M = 1.13 H
V2 = 1.13 d/dt (20 sin 314t)
V2 = 1.13 ×  20 × 314 × cos 314t
The maximum value of V2 = 1.13 × 20 × 314 = 7.1 kV
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Community Answer
Two coupled coils with L1 = 0.5 H and L2 = 4.0 H have a co-efficient o...
To find the maximum value of the induced EMF in coil 2, we can use the formula for the mutual inductance (M) between two coupled coils:

M = k * sqrt(L1 * L2)

Where:
M is the mutual inductance
k is the coefficient of coupling
L1 is the inductance of coil 1
L2 is the inductance of coil 2

Given values:
L1 = 0.5 H
L2 = 4.0 H
k = 0.8

We can substitute these values into the formula to find the mutual inductance:

M = 0.8 * sqrt(0.5 * 4.0)
M = 0.8 * sqrt(2.0)
M = 0.8 * 1.414
M = 1.131 H

Now, we can find the maximum value of the induced EMF in coil 2 using Faraday's law of electromagnetic induction:

EMF2 = -M * dI1/dt

Where:
EMF2 is the induced EMF in coil 2
M is the mutual inductance
dI1/dt is the time derivative of the current in coil 1

Given:
i1 = 20 sin 314t A

To find dI1/dt, we can take the derivative of i1 with respect to time:

dI1/dt = 20 * 314 * cos(314t)

Now, we can substitute the values into the formula to find the maximum value of the induced EMF in coil 2:

EMF2 = -1.131 * 20 * 314 * cos(314t)
EMF2 = -7095.76 * cos(314t)

The maximum value of cos(314t) is 1, so the maximum value of the induced EMF in coil 2 is:

EMF2(max) = -7095.76 V

Since the EMF is a negative value, we can take the absolute value to get the magnitude:

|EMF2(max)| = 7095.76 V

Therefore, the correct answer is option C) 7.1 kV.
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Two coupled coils with L1 = 0.5 H and L2 = 4.0 H have a co-efficient of coupling 0.8. Find maximum value of the inductance EMF in the coil 2 if a current of i1 = 20 sin 314t A is passed in coil 1.a)22.6 Vb)444 Vc)7.1 kVd)355 VCorrect answer is option 'C'. Can you explain this answer?
Question Description
Two coupled coils with L1 = 0.5 H and L2 = 4.0 H have a co-efficient of coupling 0.8. Find maximum value of the inductance EMF in the coil 2 if a current of i1 = 20 sin 314t A is passed in coil 1.a)22.6 Vb)444 Vc)7.1 kVd)355 VCorrect answer is option 'C'. Can you explain this answer? for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about Two coupled coils with L1 = 0.5 H and L2 = 4.0 H have a co-efficient of coupling 0.8. Find maximum value of the inductance EMF in the coil 2 if a current of i1 = 20 sin 314t A is passed in coil 1.a)22.6 Vb)444 Vc)7.1 kVd)355 VCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Two coupled coils with L1 = 0.5 H and L2 = 4.0 H have a co-efficient of coupling 0.8. Find maximum value of the inductance EMF in the coil 2 if a current of i1 = 20 sin 314t A is passed in coil 1.a)22.6 Vb)444 Vc)7.1 kVd)355 VCorrect answer is option 'C'. Can you explain this answer?.
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