Trajectory of an electron traveling near a current-carrying wire

AI Thread Summary
The discussion focuses on the trajectory of an electron traveling near a current-carrying wire, with initial values for magnetic field strength and force provided. The participant attempts to derive a formula that describes the electron's trajectory based on its distance from the wire (R), rather than time. They express that the vertical velocity remains constant while the x-component changes, leading to confusion about the relationship between velocity and time. A formula for force and acceleration is developed, but questions arise regarding the constancy of velocity as it is influenced by the magnetic field. The conversation highlights the complexities of calculating the trajectory and the need for clarity on how velocity varies in this context.
alesdiazdeo
Messages
3
Reaction score
0
Homework Statement
There's an infinite vertical wire which produces 5Amps. An electron is 0.2 meters apart with a velocity of 10^5 m/s in the same direction of the wire. The wire is creating a magnetic field which alters the trajectory of the electron. I need to know to the function which represents it.
Relevant Equations
Fm(magnetic force)=q(v x B) (charge times vectorial multiplication of velocity and magnetic field)
Without vectors it's just Fm=qvB
B(magnetic field)=nu/2pi * I/R (I=current intensity, R=distance)
nu/2pi=2*10^-7 (it's a constant)
B equals 50*10^-7 T (at first instance)
Fm equals 8*10^-20 N (at first instance)

I know Fm is perpendicular to the velocity, and I know the estimation of the trajectory (somewhat similar to the curve y=lnx).

Since I think vertical velocity will be constant, only changing the x component, I tried summing the Fm and the B formula, creating a bigger formula which I think represents the growth on the Y axis of the final desired formula dependent to R. That's what I want, not a formula that depends on time but a formula that depends of the distance to the wire (R).
electron-ej41.JPG
 
Last edited:
Physics news on Phys.org
alesdiazdeo said:
That's what I want, not a formula that depends on time but a formula that depends of the distance to the wire (R).
What is the quantity your formula should compute?

I would describe the trajectory of the electron with an x and y coordinate, where:
x is the distance to the wire
y = the distance the electron has traveled since the start of the experiment. obviously (y = vt)

x will depend on t, an easy computation with Newton's second law (F = ma)
Using y = vt, you can also make x dependent on y.
 
There are no preferences, just calculation of the trajectory is my task.

Alright, so I inserted the B formula into the Fm formula and got Fm=1.6*10^-20/R.
Divided it by the mass of the electron and got the acceleration.
Did the integral of that and got v=1,76*10^10*ln|R|+C (which I assume is 0 since R=inf -> v=0)
I thought that was a good representation of the Y axis and the X axis could be represented by 10^5 (constant) but my friend tells me that v (on the X axis) also changes with time.

So I'm lost again.
 
Last edited:
alesdiazdeo said:
Since I think vertical velocity will be constant
What makes you think that ?

##\ ##
 
BvU said:
What makes you think that ?

##\ ##
That the initial statement was that; but of course v is only constant in module, not as a vector, as it varies with F=qvB.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Trying to understand the logic behind adding vectors with an angle between them'
My initial calculation was to subtract V1 from V2 to show that from the perspective of the second aircraft the first one is -300km/h. So i checked with ChatGPT and it said I cant just subtract them because I have an angle between them. So I dont understand the reasoning of it. Like why should a velocity be dependent on an angle? I was thinking about how it would look like if the planes where parallel to each other, and then how it look like if one is turning away and I dont see it. Since...
Back
Top