Two metallic wires P1 and P2 of the same material and same length but different cross sectional area A1 and they to join together and connected to a source of EMF. Find the ratio of the drift velocity Sobti electrons in the two wires when they are connected in (i) series (ii) parallel
Answers
Two metallic wires P1 and P2 of the same material and same length but different cross sectional area A1 and they to join together and connected to a source of EMF. Find the ratio of the drift velocity Sobti electrons in the two wires when they are connected in (i) series (ii) parallel
I = nevA
v = velocity A = area of cross section
let say P1 has A1 area v1 - drift velocity , I1 - Current
& P2 has A2 area & v2 drift velocity , I2 - current
Case 1 - Series
As we know current in series conductor = equal
so
I1 = I2
=> nev1A1 = nev2A2
=> v1/v2 = A2/A1
So ratio of the drift velocity Sobti electrons in the two wires when they are connected in Series = reciprocal of their cross sectional area
Case 2 - parallel
in parallel R ∝ Length/Area
R ∝ 1/Area ( as length is same in two wires)
I = Emf/R
=> I ∝ Area (as EMF is same)
I1/I2 = A1/A2
=> I1 * A2 = I2 * A1
=> nev1A1 * A2 = nev2A2 * A1
=> v1 = v2
=> v1/v2 = 1
in case of parallel drift velocity Sobti electrons is same in both wires
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