Drift Speed of Electrons In a wire

Two wires X and Y have the same resistivity, but their cross sectional areas in the ratio 2:3 and lengths in the ratio 1:2 They are first connected in series and then in parallel to a dc source Find out ratio of drift speeds of electrons in two wires for the two cases.

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


Comments

  1. Anonymous27 June 2018 at 03:01

    Garg Associates produce a wide variety of High Performance Wires and Cables ranging from ultra-miniature Fluoropolymer (PTFE, ETFE and FEP) equipment wire, thermo couple cable, high powered shielded Multicore cables to high speed data bus, low loss and Ethernet cables. Whether it is custom designed or a standard product, there is a solution to the most demanding environment and application.
    PTFE INSULATED EQUIPMENT WIRES
    fluropolymer wires suppliers

    ReplyDelete

Post a Comment

Popular posts from this blog

Hyperbolic Paraboloid

Image
Graphs and Level curves of functions of Two variables Definitions The set of points (x,y) in the plane where a function f (x,y) has a constant value f(x,y)=c is called a level curve of f The set of all points (x,y,f (x,y)) in space, for (x,y) in the domain of f, is called the graph of f The graph of f is called the surface z=f (x,y) The equation of the following hyperbolic paraboloid is `z=50+x^2-y^2`
Read more

Renewable Energy-Solar

The conventional energy sources are depleting at an exponential  rate .The energy crisis is a major concern for the nation around. The coal will last long only for 100 years or less petroleum resource will be exhausted nearly in 50 years time. The oil producing countries it self is moving towards the introduction of renewable energy sources , major among them is Solar energy. The energy production in the sun is  by the  nuclear fusion , hydrogen in the core of sun is converting in to heavier nucleus helium during this process the nuclear binding energy is liberating in the form useful energy . The plants can absorb the visible light and utilize it  for photosynthesis . The use of solar energy by natural means is coming only 1 to 2 % , rest of the energy is un utilized The solar energy capturing technique (Photo Voltaic) was introduced by Charles Fritts   in the year 1883 The solar energy can be  utilized in the following ways 1.  ...
Read more