Two conductors, both having same length and same area of cross-section, are joined in parallel as
Answers
case i) Series
In series combination current I through each resistor will be the same
Current I= neAVd
n=number of electrons per unit volume
e=Charge of an electron
A=Area of cross section of wire
Vd= Drift speed
Vd= I / (neA)
Vd1= I / (neA1) --------------(1)
Vd2= I / (neA2) --------------(2)
Note that 'ne' is same for both the wires since the resistivity same means same material
From 1) and 2) Vd1 / Vd2 = A2 / A1 ie Ratio of drift speed is 3:2
case ii) Parallel
In Parallel combination potential 'v 'through each resistor will be the same
Current I= neAVd
By ohms Law v=IR
ie v= (neAVd) R
Vd= v / RneA and R=ΡL/A
R1=ΡL1/A1
R2=ΡL2/A2
Ρ=resistivity
Vd1= v / (R1 neA1)---------------(3)
Vd2= v / (R2 neA1)---------------(4)
From 3) and 4) Vd1 / Vd2 = L2/L1 ie Ratio of drift speed is 2 : 1