Electrical Engineering - Alternating Current and Voltage - Discussion

Discussion :: Alternating Current and Voltage - General Questions (Q.No.2)

2. 

The conductive loop on the rotor of a simple two-pole, single-phase generator rotates at a rate of 400 rps. The frequency of the induced output voltage is

[A]. 40 Hz
[B]. 100 Hz
[C]. 400 Hz
[D]. indeterminable

Answer: Option C

Explanation:

No answer description available for this question.

Vineeta Verma said: (Jan 8, 2011)  
f = pn/120
f = 400*60*2/120
f = 400 HZ

Mahendra said: (Mar 3, 2011)  
From where did the 60 came please tell me vineeta verma.

Raj said: (Mar 3, 2011)  
Because we have to change rps to rpm.

Talha said: (May 7, 2011)  
Thanks for that answer.

Vipul Parmar said: (Aug 17, 2011)  
F = PN/120
= 400*60*2/120
= 400Hz Because 400*60 rps= 400 rpm.

Yanusha A said: (Sep 22, 2011)  
N=120F/P
N=400rps=400*60rpm
p=2
F=NP/120
=400*60*2/120
=400HZ

Sandeep said: (Nov 21, 2011)  
P=2
N= 400 r/s (rps )= 400 r/(m/60)=400*60 r/m
=400*60 rpm
we know f = N P /120= 400*60*2/120=400 Hz.

Mau Chau said: (Feb 16, 2012)  
Thanks raj.

Bhavesh said: (Mar 13, 2012)  
Sandip your answer is correct.

Pukhraj said: (Mar 17, 2012)  
Thanks vineeta.

Vinothkumar said: (Aug 28, 2012)  
Thanks sandeep.

Mustafa said: (Sep 3, 2012)  
If this is a single phase generator , how are we considering the angle to be 120 degrees?

Ribka A said: (Sep 15, 2012)  
In three phase generators we will consider the angle between three coils should be 120 degrees.

Amarendra Dash said: (Aug 28, 2013)  
We know N = 120F/P.

SO F = N*P/120.

Here n = 400rps(revolution per second).

n = 400*60rpm(rps=Hz=60*rpm).

Thus,

F = 400*60*2/120.

F = 400Hz answer.

Ahmed said: (Feb 13, 2014)  
n= 120*f/p.
n : rapid per minute.
f: frequency.
p:no of poles.

n=400*60(rps) =24000(rpm).

f=n(rpm)*p/120.
f=24000*2/120.
f=400 HZ.

Thiru Punk said: (Apr 19, 2015)  
n(rps) = 400 rps.
p(pole) = 2.

f = (pn/2).
f = (2*400/2) => 400Hz.

Ch Nikhil Chakravarthy said: (Apr 19, 2015)  
Since f=1/T.

Here f is frequency.
T is time in seconds.

Girishgowda said: (Jun 27, 2015)  
p = 2.
n = 400.

rps its converted in to rpm its value is 6.66 rpm.

Then f = pn/120.

= 2*6.66/120.
= 0.111 hz.

Navya said: (Aug 20, 2015)  
Where 1sec=1/60min. But how you multiplied 60 in the speed.

Mrityunjay said: (Aug 20, 2015)  
Please any one tell from where 2 is came?

Kalai Sasi said: (Sep 26, 2015)  
Its a number of poles.

Jansi said: (Jan 24, 2016)  
Here given data is:

No. of poles = 2;

Speed (N) = 400 rps;

Usually speed is calculated in rpm. So here we convert 400 rps (revolution per second) in terms of rpm (revolutions per minute).

As 1 min = 60 sec; we multiply 400x60 rpm;

As we know N = 120f/p.

f = np/120;

f = 400x60x2/120.

f = 400 hz.

So hope no one has any doubts regarding this explanation.

Rakshith said: (Aug 20, 2016)  
As we all know,

Ns = ( (120 * f) /p); Here Ns is in rpm. Therefore,

Ns = Ns/60 rps.

So,

Ns = ((2 * f)/p),
And f = ((p * ns)/2),

f = 2 * 400/2,

f = 400Hz.

Hassan said: (Aug 29, 2016)  
How did you guys get that 120?

Fatima said: (Dec 13, 2016)  
@Hassan.

Formula contains Ns syncronous speed ,Ns = (( 120 * f ) /p).

Bhanu said: (Feb 7, 2017)  
Great job @Jansi.

Waheed Ullah Khattak said: (Feb 16, 2017)  
If we change RPS to RPM then we should have to divide by 60.

Surya said: (Aug 16, 2017)  
N= 120f/p.
F= 400*60*2/120.
F= 400.

Sunnyleon said: (Oct 2, 2017)  
Thank you @Sandeep.

Kiran said: (Dec 7, 2017)  
rps=400*60=24000=Ns.

P=2
Ns=120f/p
120*f/Ns*p
f=Ns*p/120
f=24000*2/120
f=400.

Feroz Khan said: (May 10, 2018)  
1rpm=60rps.
so 1rps 1/60 rpm and,
400rps=400 * 1/60 rps.

I think the answer is wrong @Kiran.

D.Jyothi said: (Aug 30, 2018)  
As per the definition, frequency means that the number of cycles completed by one rotation.

Asim said: (Sep 2, 2018)  
Good explanation @Rakshith.

Mehr said: (Apr 19, 2019)  
For rpm; Simply convert this to the minute, we multiply 60 with rps 400*60.

Shoon said: (Aug 24, 2019)  
1min = 60sec.

If 400rps then 400/60 rpm.

As from small quantities to bigger quantities we do division, from bigger quantities to small we do multiplication.

Kindly explain it.

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