Please help and do it step by step all parts of questions and use:
T = time(s)
I=current (amps)
Q=net charge on object (Coulombs)
N=no electrons (and write if added or removed from object and how)
E=elementary charge
Calculate the number of free electrons per metre length of wire if a current of 2.0A produces a drift velocity of 1.0 x 10^-3 ms-1.
As physics - bobpursley Tuesday, December 12, 2017 at 10:27am
current=driftevelocity*area*electrondensity
but number electrons per lenth=electron dinsity)*area
the equation i=anev
n=work out
i=2
a=???
v= 1.0 X 10^-3 ms-1
was what i thought at first but then 2 values were missing when only one should be then you said number "NUMBER electrons per lenth=electron dinsity)*area"
but i dont know the density of the electrons or the area pelase help
As Physics - cylinder today at 10:34am
is there a way to work this out?
As Physics - cylinder today at 10:45am
i cant find the numbers for the equation yo gave me
"NUMBER electrons per lenth=electron dinsity)*area"
As Physics - cylinder today at 11:10am
please help
Thank you Bob i get the 4x thing now, this is the only question i cant get now please help someone
number of electrons = coulombs * electrons/coulomb
but we know
electrons/coulomb = 1/1.6*10^-19coulombs
= 10/1.6*10^-18
= 6.25*10^18 electrons/coulomb
we know that 2 coulombs/second pass a point which is 12.5*10^18 electrons per second
how many seconds to go a meter?
1/v = 1/1*10^-3 = 1000 seconds/meter
so
12.5 *10^15 electrons in that meter.
Calculate the number of free electrons per metre length of wire if a current of 2.0A produces a drift velocity of 1.0 x 10^-3 ms-1. <<
You are given the drift velocity = 1.0 x 10^-3 m/s.
So it would take 1/(1.0 x 10^-3 m/s) = 1000 seconds to "flush out" all the electrons currently in a one metre length of wire.
2.0 A = 2.0 coulombs/second
So a 1m length of wire contains (2.0 C/s * 1000 s) = 2000 C worth of electrons
Each electron contributes 1.602 x 10^-19 C of that, so your 1 m length of wire represents
2000 / (1.602 x 10^-19) ≈ 1.25 x 10^22 electrons/metre length
I think Prof Damon erred in his last step,
delectrons/meter=1000sec/m*12.5*10^18elet/sec=12.5e21 electrons/m, which is the same as my number 1.25e22 electrons/meter
Yes, you are right. I should have multiplied electrons / second times seconds / meter
Thank you so much both of you really helpful!! :)
To calculate the number of free electrons per meter length of wire, you can use the formula:
Number of electrons per length = (current x area) / (elementary charge x drift velocity)
Let's go through the steps to find the answer:
Step 1: Find the value of current (I) and drift velocity (v) given in the question.
I = 2.0A
v = 1.0 x 10^-3 m/s
Step 2: Determine the area (A). The question doesn't provide the area, so we need to find it or make an assumption.
Since we are dealing with a wire, we can assume a circular cross-section. In that case, the area (A) of the wire can be calculated using the formula:
A = πr^2, where r is the radius of the wire.
If you have the value of the radius, substitute it into the formula to find A. If not, you might need to refer to the given information, textbook, or consult your instructor.
Step 3: Determine the elementary charge (e).
The elementary charge (e) is a fundamental constant in physics and has a value of 1.6 x 10^-19 Coulombs.
Step 4: Substitute the values into the formula:
Number of electrons per length = (2.0 x A) / (1.6 x 10^-19 x 1.0 x 10^-3) electrons/m
Calculate the value of 2.0 x A and divide it by 1.6 x 10^-19 x 1.0 x 10^-3 to get the final answer. Make sure to use the correct units.
Remember, in this step-by-step process, having the values for area (A) and radius is essential. If you don't have those values, you'll need to gather more information or make the appropriate assumptions.