# Electric and magnetic fields

1. Mar 23, 2015

### vysero

1. The problem statement, all variables and given/known data

The below region of space shown has uniform electric and/or magnetic fields, dependent on the conditions listed for cases A-G. Identical positively charged particles enters these regions with the same velocity.

Rank the magnitude of the force on the particle just after it enters these regions for cases A-G from greatest to least.

2. Relevant equations

F = qE + qv x B
F = qE
Fb = qvBsin(*)

3. The attempt at a solution

A) Since the particle is positive(+) I said there would be a force F namely ( ---> ) on the particle.

B) When only B is present there is no force on the particle, Fb = qvBsin(0) = 0. This is because both B and V are parallel.

C) Same as A: ( ---> )

D) Same as A: ( ---> )

E) Here the direction of the force changes but its magnitude remains the same so: ( <--- )

F) There is an upwards force in this case. However, its magnitude is the same as was in A.

G) I have this as being two forces on the particle so G is the largest.

Overall I ranked them as follows: G>A=C=D=E=F>B

Not sure if I did these correctly any help would be appreciated.

2. Mar 23, 2015

### Dick

Sounds ok to me.

3. Mar 23, 2015

### vysero

Wait... you mean I got it right.. like on my own ._. I think I will go have a drink!

4. Mar 23, 2015

### Dick

Sure, have a drink. I can't see anything wrong with your logic.