How Does an Electric Field Cancel Out Magnetic Force on an Electron?

AI Thread Summary
To cancel the magnetic force on an electron moving in a magnetic field, the electric field must be equal in magnitude but opposite in direction to the magnetic force. The relationship can be expressed as E = vB, where E is the electric field, v is the velocity of the electron, and B is the magnetic field strength. It's crucial to consider the vector forms of the equations to accurately determine the direction of both forces. The electric field direction must be opposite to the velocity of the negatively charged electron to effectively counteract the magnetic force. Understanding the relative directions of the vectors involved is essential for achieving a straight path for the electron.
jakeowens
Messages
34
Reaction score
0
What magnitude and direction would an electric field, E, need to be to cancel out the force on an electron traveling with speed, v, in magnetic field B?

I know the formula for the force on an electron in a magnetic field is F=qvB. The formula for the force on an electron in a electric field is F=qE. can i just set the two equal to each other? giving me qE=qvB, divide by q, giving me E=vB? is that right?
 
Physics news on Phys.org
Your answer is supposed to have magnitude and direction, so you need to use the vector forms of the equations that you list. Other than that, you are on the right track. BTW, what is the shape of the path of an electron moving with velocity v in a magnetic field? When you get your E(t) field correct, the electron will go back to just a straight path with velocity v.
 
I don't know any information other then what was given, that's why I'm slightly confused, I am just getting messed up in the directions
 
The electric field has to flow in a direction (from positive to negative) in the same direction as the force from the magnetic field correct? that way the electron will be attracted back, canceling out the force from the magnetic field, allowing it to travel in a straight path. Am i right?
 
jakeowens said:
The electric field has to flow in a direction (from positive to negative) in the same direction as the force from the magnetic field correct? that way the electron will be attracted back, canceling out the force from the magnetic field, allowing it to travel in a straight path. Am i right?

Actually because the electron has a negative charge, the electric field will point in the direction opposite to the direction of the velocity. I think what the question is after is the relative directions of the vectors involved, so sketch a quick diagram and make an assumption of what direction the E field is, then figure out the required direction of B.

Note: The magnetic force is NOT F=qvB. Use the vector version of this equation!

-Dan
 

Thread 'Rolling without slipping on a curved surface'

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 .
View full post »
Thread 'Voltmeter readings for this circuit with switches'

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...
View full post »
Thread 'Trying to understand the logic behind adding vectors with an angle between them'

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...
View full post »

Similar threads

Making sense of sequence of ideas in MIT OCW's 8.02 notes on Faraday
Replies
1
Views
1K
Induced current and force on circular loop in varying magnetic field
Replies
4
Views
1K
Magnetic field due to electric wire
Replies
6
Views
1K
Determine the force with which the magnetic field of a coil acts on an infinitesimal cube of iron
Replies
6
Views
987
What is the induced magnetic force on this closed current loop?
Replies
12
Views
2K
Electron passing through a magnetic and an electric field
Replies
2
Views
2K
Why is magnetic field B along a straight wire circular not radial?
Replies
14
Views
3K
Velocity along the cylinder axis
Replies
18
Views
2K
Electric and Magnetic field acting on an electron
Replies
25
Views
5K
Electric field in a rotating rod in a magnetic field
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top