How Does the Right Hand Rule Determine Magnetic Force Direction?

[dagg3r]

hi i have a few general questions on the right hand rule,
1. if a charged particle enters a magnetic field going from bottom left to top right at an angle of 45 degrees, and the direction of the current is vertically up how do we determine the force using the right hand rule?

2. a wire which carries a current is placed into a magnetic fileds with right angles to the wires, is there an orientataion for the wire so there would be no magnetic force? I am guessing the the wire to be parallel to the magnetic field?

some electronics questions i got stuck on
1.
A 12.0V battery is about to be connected to a series circuit containing a 10.0 ohm resistor and a 2.00H inductor. after the battery is connected how long will the current rech 50% of its final value?

i did this
.5I = emf/R (1 - e^(-Rt/L))
I=12/10
.6 = (12/10) (1 - e^(-10t/2)) solved for t
t=0.14 seconds

2. A strong electromagnet has a field of 1.60T and a cross sectional area of 0.200m^2. A coil having 200 turns and a total resistance of 20.0 ohm is placed in the electromagnet. If the current in the electromagnet is turned off in 20.0 ms what is the average current induced in the coil?

i used the formula E=-nbAcos(theta)/ T
then having the EMF, worked out the current to be 160 amps? surely i am doing something wrong?

 

[H_man]

1) http://www.pa.msu.edu/courses/1997spring/PHY232/lectures/magforces/righthandrule.html

2) Yup... If the the current is parallel to the B field lines no force.