# Electrical Engineering - RL Circuits - Discussion

### Discussion :: RL Circuits - General Questions (Q.No.3)

3.

In a series RL circuit, 12 V rms is measured across the resistor, and 14 V rms is measured across the inductor. The peak value of the source voltage is

 [A]. 18.4 V [B]. 26.0 V [C]. 2 V [D]. 20 V

Explanation:

No answer description available for this question.

 Samuel Amu said: (Feb 23, 2012) In a series circuit, current is constant. assume a unity current flowing in the cct., then XL=VL/I, nb I=1(assumed). XL=14/1=14 and R=VR/I=12. cct impedance Z=(R^2+XL^2)^(-2) Z=(12^2+14^2)^(-2)=18.439 peak voltage: Vp=IZ Vp=1x18.439 Vp=18.439 v So answer is Option A.

 Chris said: (Mar 22, 2012) Current can't be constant, its a AC signal. If so, Z(L) would be zero. But option B isn't correct either cause RMS isn't the same as peak.

 Gerald said: (Aug 29, 2012) The relationship between peak and rms voltages is given as: Vrms = (Vpeak)/sqrt(2). As a continuation to Samuel Amu's solution, his answer (18.439V) is still the rms value. Transforming to peak value gives: Vpeak = (Vrms)*sqrt(2) = 18.439*sqrt(2) = 26.07 Volts.

 D.P.Mishra said: (Jan 15, 2013) Sqrt(VL^2+VR^2)=Vrms. i.e sqrt12^2+14^2=sqrt340. Vp=sqrt2*Vrms. i.e Sqrt(2*340)=sqrt680=26.0V approx.

 Pravin said: (Feb 17, 2014) Consider, Two voltage are connected in series so the two are addition so simple as this Que. 12+14 = 26.

 Pavan said: (Apr 15, 2014) While taking RL load the relation ship can not be said by sqrt 2 times then rms value. Because for RL circuit V can be measured by Laplace which never in terms of Sin it will be exponential in nature which rms is not 1/sqrt 2. otherwise answer is taken w.r.t. fundamental formula: V = (12^2+14^2)^0.5. Satisfies all condition.

 Ashoka.J said: (Jan 14, 2015) In series circuit v = v1+v2. So total volume is 12+14 = 26. 26/2 = 13.V, peak = 13*1.414 = 18.38 v.

 Chaitanya said: (Jul 7, 2015) Sqrt(VL^2+VR^2) = Vrms. i.e sqrt 12^2+14^2 = sqrt 340. Vp = sqrt 2*Vrms. i.e Sqrt(2*340) = sqrt 680 = 26.0 V approx.

 Guesh Berhe said: (Aug 11, 2015) I am satisfied by this question.

 Tejal said: (Oct 23, 2015) Two voltage are connected in series so the two are addition so simple as this question: 12+14 = 26. But 12 and 14 are RMS values, n in Q? Asked peak value of source. Thus peak values can be calculated from RMS values from the formula, which implies Vp = VRMS*2. Answer is 36.7.

 Khushbu said: (Jan 29, 2016) @Tejal. You should write srrt(2) instead of 2 answer is correct.

 Karuna said: (Apr 29, 2016) Really, they asked the peak value. So, the answer is (12 + 14)1.414 = 36.764.

 Asad said: (Sep 4, 2016) V = sqrt(Vr2 + Vl2), V = sqrt(12 pow 2 +14 pow 2), V = sqrt 340, V = 18.43, Vpeak = 18.43 x 1.41, Vpeak = 26 volts.

 Manish Sharma said: (Sep 1, 2018) 26.00v is the correct answer.