Posted by J on Monday, February 25, 2008 at 5:27pm.
A beam of protons is accelerated through a potential difference of 0.745 kV and then enters a uniform magnetic field traveling perpendicular to the field. (a) What magnitude of field is needed to bend these protons in a circular arc of diameter 1.75 m? (b) What magnetic field would be needed to produce a path with the same diameter if the particles were electrons haveing the same speed as the protons?
ok for part (a) I confused on what equation to incorporate all the givens! I am lost! and for part (b) you would just need to change the mass of the the protons to the mass of electrons or is there more to that?
Physics - Damon, Monday, February 25, 2008 at 6:16pm
The kinetic energy of the proton is (1/2) m v^2
Therefore (1/2) m v^2 = 745 volts * charge of proton
That gives you v, the speed of the proton.
Now use your force on a particle in a magnetic field to get the radius of path (if you do not have the equation in your book) If you do, just skip to the end of the next paragraph.
F = q v B if B perpendicular to v
= mass * centripetal acceleration = m v^2 /R.
So R = m v /(q B)
That is all you need.
In part B m changed for the proton. That changes the velocity from (1/2) m v^2
and also makes a change in the radius equation.
(1/2) m v^2 = q V
v = sqrt (2 q V/m)
then for th radius
R = m v/(qB) = sqrt(2 q V m)/(q B)
so the radius goes up with sqrt(m)
of course the sign of q changed, but that only changes the direction, not the radius.
Answer This Question
More Related Questions
- Electromagnetism - A particle with a mass of 6.64x10^-27 kg and a charge of +3....
- Physics - An á-particle has a charge of +2e and a mass of 6.64 10-27 kg. It is ...
- Physics - An -particle has a charge of +2e and a mass of 6.64 10-27 kg. It is ...
- physics - In earlier learning sequences we described how a static magnetic field...
- eletromagnets - In earlier learning sequences we described how a static magnetic...
- magnetism - In earlier learning sequences we described how a static magnetic ...
- Physics - An electron beam of a TV picture tube is accelerated through a ...
- physics - speed of electron in magnetic field - A beam of electron is ...
- PHYSICS I NEED HELP - Consider free protons following a circular path in a ...
- Physics - A singly charged positive ion has a mass of 2.74 10-26 kg. After being...