Question

Derive the formula of equivalent resistance of series combination of resistor

Answer 1

Answer:

Req=R1+R2+R3

Explanation:

In series combination,

According to ohm's law

V1=IR1-(1), V2=IR2-(2), V3=IR3-(3)

Let Req is equivalent resistance.

So V=IReq-(4)

But we know that inseries connection

V=V1+V2+V3-(5)

SUBSTITUTE the values (1), (2)&(3)&(4) in (5)

Then IReq=IR1+IR2+IR3

cancel (I)on both sides

Then Req=R1+R2+R3

Answer 2

Answer:

Explanation:

Consider I is the current through the circuit

R1,R2,R3 are the resistance of three individual resistors

V1,V2,V3 are the potential difference across R1,R2,R3 respectively

Total potential difference across a combination of resistors in series is equal to the sum of potential difference across the each resistor v=V1+V2+V3 equation one

Applying of ohms law to the whole circuit we have V=IR equation 2

Applying ohms law for all the resistors

V1=IR1 equation 3

V2=IR2 equation 4

V3=IR3 equation 5

Adding the equation 3,4 and 5

V1+V2+V3=IR1+IR2+IR3

V=I(R1+R2+R3)

IR=I(R1+R2+R3)

Rs=R1+R2+R3