Question

1. only choose mcq

2. Four resistors, A: 25 ohm, B: 50 ohm, C: 10 ohm and D: 80 ohm are connected in series. A battery of 10 V is applied across the combination. If current is passed through the combination for one hour, heat generated is minimum for which resistor?

   	A.	C
   	B.	A
   	C.	D
   	D.	B

Answer 1

Answer is Resistor C

equivalent resistance is given by

R=25+50+10+80

R=165 A

Current flowing in the circuit is

I=V/R =10/165 =0.060606 A

Heat generated in each resistor is

Q_A =I²R_At =0.060606²*25*(1*60*60) =330.58 J

Q_B =I²R_Bt =0.060606²*50*(1*60*60) =667.16 J

Q_C =I²R_Ct =0.060606²*10*(1*60*60) =132.23 J

QD=I²R_Dt =0.060606²*80*(1*60*60) =1057.85 J

Therefore answer is A. C