The magnetic field strength required to oscillate an electron

[cmcd]

Homework Statement

"An electron is accelerated by a potential difference of 1 V and is injected into vacuum. How strong should the magnetic field in a vacuum be if you want the electron to circle along a loop with a radius of 10^-1m? Please indicate the direction of the magnetic field"

Homework Equations

PE = KE
for speed

F_centripetal =( mv^2) / r
for force

B = qv/F
for field strength

The Attempt at a Solution

v = sqrt(2qV/m)
v= 5.93 E5 m/s

F = 3.2 E-18 Newtons

B = 3 E4 Tesla

 

[cmcd]

Not a textbook question...

 

[rude man]

Homework Statement

B = qv/F
for field strength

Better check that one.

 

[berkeman]

Homework Statement

"An electron is accelerated by a potential difference of 1 V and is injected into vacuum. How strong should the magnetic field in a vacuum be if you want the electron to circle along a loop with a radius of 10^-1m? Please indicate the direction of the magnetic field"

Homework Equations

PE = KE
for speed

F_centripetal =( mv^2) / r
for force

B = qv/F
for field strength

The Attempt at a Solution

v = sqrt(2qV/m)
v= 5.93 E5 m/s

F = 3.2 E-18 Newtons

B = 3 E4 Tesla

Better check that one.

It is a good practice to carry units along for all quantities in all of your equations. If you had done so, you would have caught this error that rude man is pointing out...

 

[rude man]

I hope you listen to berkeman. There's nothing more important than carrying units along. Then you can check expressions term-by-term for agreement and the correctness of the answer. Which is (one reason) why I oppose using numbers instead of symbols until the very end, and why I abhor labeling e.g. a dependent voltage source as "10I" where I is current and the "10" is meant to be some impedance.