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.

 

[quicknote]

The right hand rule is a way to determine the direction of a magnetic force on a charged particle or a current-carrying wire in a magnetic field. It is based on the fact that the magnetic field lines around a current-carrying wire or a magnet form a circular pattern around the wire or magnet.

1. To determine the force on a charged particle using the right hand rule, you would point your right thumb in the direction of the particle's motion, your index finger in the direction of the magnetic field, and your middle finger will point in the direction of the magnetic force.

2. In order to have no magnetic force on a wire in a magnetic field, the wire would need to be parallel to the magnetic field. This is because the angle between the wire and the field would be 0 degrees, and according to the formula F=qvBsin(theta), the force would be 0.

For the electronics questions:

1. Your calculation for the time it takes for the current to reach 50% of its final value looks correct. However, it is important to note that this assumes the inductor is ideal and has no resistance. In reality, there will be some resistance in the inductor which will affect the time it takes for the current to reach 50% of its final value.

2. Your calculation for the average current induced in the coil looks correct. However, it is important to note that this is the maximum current induced in the coil and it will rapidly decrease as the magnetic field decreases. Additionally, the formula you used, E=-nbAcos(theta)/T, is for a rotating coil in a magnetic field, not a stationary one. The correct formula to use in this case would be E=-N(dPhi/dt), where N is the number of turns in the coil and dPhi/dt is the rate of change of magnetic flux through the coil.