Electrical Engineering - Inductors - Discussion

Discussion :: Inductors - General Questions (Q.No.21)

21. 

The inductance of an iron-core coil decreases if

[A]. the number of turns is decreased
[B]. the iron core is removed
[C]. the length of the coil decreases
[D]. none of the above

Answer: Option A

Explanation:

No answer description available for this question.

Kirthikumar Rao said: (Nov 23, 2011)  
Wkt LI=NQ
L=inductance of the coil
I=current
N=no of turns of the coil
Q=flux
as inductance is directly proportional to no of turns

Deep Sandholia said: (Nov 26, 2013)  
Flux is directly proportional to no.of turns.

Dipak said: (Dec 2, 2014)  
L = N^2/R.
L = INDUCTANCE.
N = NUMBER OF TURNS.
R = RELUCTANCE OF CORE.

Eng. S.T.Arif said: (Apr 29, 2015)  
Inductance (Physical property of a coil) L = U.N2.l.A.

U = Permeability of core,
N2 = NxN (Number of turns).
L = Length of coil.
A = Cross sectional area of coil.

So if to decrease L.

You decrease (remove of iron core).

Reduce N turns of coil.
Reduce length of coil.

The correct answer is not given in the question.

Sandeshg said: (Jun 11, 2015)  
Answers A, B are correct. Air core has less permittivity as compared to iron core hence lesser the permittivity lesser the inductance of the coil.

Svn said: (Jan 9, 2017)  
Right answer is both A and B.

Deepak said: (Jan 19, 2018)  
Here, L=£N^2A/L.

Haris said: (Jan 11, 2020)  
L = (permiability)*(no of turns)^2*Area/Length.
L = u*N^2 * A/length.

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