The core of a two-winding transformer is subjected to a

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The core of a two-winding transformer is subjected to a magnetic flux variation as indicated in the figure given below.

The induced emf (e_rs) in the secondary winding as a function of time will be of the form

Correct Option: B

Induced emf in secondary, e_rs = - N₂	dφ
	dt

From given curve,
φ = 0.12 t ;    0 < t < 1
0.12 ;    1 ≤ t ≤ 2
– 0.24 t + 0.6 ;    2 ≤ t ≤ 2.5
∴ e_rs = – 200 × 0.12 = – 24;    0 < t < 1
e_rs = – 200 × 0 = 0;    1< t < 2
e_rs = – 200 × (– 0.24 + 0) = 48;    2 ≤ t < 2.5
Alternately
During 0 < t < 1 sec,

E₁ = -	dφ	= - 0.12 V
	dt

E₂ and E₁ are in hence opposition,

or F	E₁	=	N₁	=	100	or , E₂ = 2E₁ = 0.24 V
	E₂		N₂		200

During 1 < t < 2, = -	dφ	= 0 , then E₁ = E₂ = 0
	dt

During 2 < t < 2.5

E₁ = -	dφ	= 0.24 V
	dt

Then, E₂ = 0.48 V
Hence the induced (e_rs) in line secondary cruidip could be of the form as given in choice (a).