Electrical Engineering - Transformers - Discussion

Discussion :: Transformers - General Questions (Q.No.20)

20. 

When a 200 load resistor is connected across the secondary winding of a transformer with a turns ratio of 4, the source "sees" a reflective load of

[A]. 50
[B]. 12.5
[C]. 800
[D]. 0

Answer: Option B

Explanation:

No answer description available for this question.

Satish said: (Dec 10, 2010)  
source sees a reflective load= with respect to primary.
Hence, 200/16=12.5 (z/k*k)

Motiur said: (Dec 16, 2011)  
As k=rt of r1/r2

Tarnjeet Singh said: (Jan 6, 2012)  
Please explain it.

Vasu said: (Feb 5, 2012)  
k = sqrt (R/r)
4 = sqrt (200/r)
16 = 200/r
r = 12.5

Raju Saikh said: (Oct 13, 2012)  
Turns ratio=k= n2/n1
& n2/n1=sqrt(r2/r1)
so, k=sqrt(r2/r1)
k*k=(r2/r1)
here, r2=200ohm;& k=4
so, 4*4=(200/r1)
r1=200/16
=12.5

Rani said: (Sep 7, 2014)  
What is correct formula to this problem?

Jagadeesh said: (Dec 13, 2015)  
Turns ratio k = N1/N2,

Transformation ratio K (capital k) = N2/N1.

So, K = 1/k.

R2' = R2/K^2;

Here K = 1/k = 1/4;

R2' = 200/(1/4)^2 = 3200, which is not in option.

Ranjan said: (Apr 22, 2016)  
How to solve the below problem, can anyone help me?

Suppose that two AC waves have the same frequency but differ in phase by exactly 1/20 of a cycle. What is the phase difference between these two waves?

Shiju said: (Oct 25, 2016)  
@Jagadeesh answer is very correct explanation.

If turns ratio 4 means vp/vs = 4 i.e vp = 4 * vs. If 200 ohm load then vs/200 is the current drawn at secondary So at primary the current Ip will be 1/4 of secondary current = vs/200/4 = vs/800.

Then reflective load = Vp/Ip = 48Vs/Vs/800 = 3200.

Shiju said: (Oct 25, 2016)  
@Ranjan,
I think it will be 18 degrees i.e total 360 degrees so 360/20 = 18.

Amani Naidu said: (Feb 16, 2017)  
Clear explanation, Thanks @Jagadeesh.

Answer is 3200.

Ali Butt said: (Aug 4, 2019)  
R2=R1k^2.
R1=R2/k^2.
R1=200/(4)^2.
R1=200/16.
R1=12.5.

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