Particle through magnetic field

AI Thread Summary
A particle with a charge of +3e enters a magnetic field of 0.80 T at a speed of 100,000 m/s, resulting in a circular motion with a radius of 0.1 m. The centripetal force equation, F = m(v^2/r), is set equal to the magnetic force equation, F = QvB, allowing for the calculation of the particle's mass. Rearranging the equations leads to the formula m = rQB / v. Substituting the known values yields a mass of 3.84 × 10^-25 kg, confirming the calculation's accuracy. The solution is validated, and confidence in the answer is encouraged.
BadatPhysicsguy
Messages
39
Reaction score
0

Homework Statement


A particle enters perpendicular to a magnetic field with a speed of 100,000 m/s. The magnetic field has a strength (B) of 0.80 T. The particle starts doing a spinning motion with an 0.1m radius. The particle charge is +3e (three elementary charges). Calculate the mass of the particle.

Homework Equations


Since it does a spinning motion, we need the formula for centripetal motion. F=m(v^2/r). We also need a formula that gives us F based on B and Q (charge) and v (speed). For that we have F = QvB.

The Attempt at a Solution


We set them equal.

m(v^2/r)=QvB and we can take off one v.
m(v/r)=QB, we move the things around so we have m alone
m*v = rQB => m = rQB / v

We enter everything that is known and we get:

0.1 * (3*1.6*10^-19) * 0.80 split by 100,000.

Result: 3.84 × 10^-25 kg. Am I correct?
 
Physics news on Phys.org
Before we answer your question, do you think you are correct?
 
cheah10 said:
Before we answer your question, do you think you are correct?
I do!
 
Ok, actually whenever you believe you are correct, you should just be confident and not doubt yourself.
You are correct in this question!
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top