Three resistors of resistances R1 , R2 and R3 are connected (i) in series, and (ii) in parallel. Calculate the equivalent resistance of combination in each case
Answers
Answer:
Req = R1+R2+R3 in series
and in parallel
1/Req = 1/R1+1/R2+1/R3
Req = (R1R2R3)/(R2R3 + R1R3 + R1R2)
Explanation:
Three resistors of resistances R1 , R2 and R3 are connected (i) in series,
connected in series so current flowing through each resistor =I
potential drop across each resistance
= IR1 ,IR2, IR3
total potential drop = IR1 +IR2+IR3
=I(R1+R2+R3)
total potential drop = I (Req)
equating both
I (Req) = I(R1+R2+R3)
Req = R1+R2+R3
in parallel
let say current flowing across each resistor I1 , I2 , I3 respectively..
in parallel potential drop= same across all resistor = V
I1 = V/R1
I2=V/R2
I3= V/R3
total current I = (I1+I2+I3)
= V/R1 + V/R2 + V/R/3
= V(1/R1+1/R2+1/R3)
total current I =V/Req
equating both
V/Req = V(1/R1+1/R2+1/R3)
1/Req = 1/R1+1/R2+1/R3
Req = (R1R2R3)/(R2R3 + R1R3 + R1R2)