Couple physics questions....?

Question

A 5.3×10−9 kg particle carrying a charge of 3.2×10−6 C is accelerated by a potential difference of 3,200 V from rest. It then passes into a uniform magnetic field of strength 4.5×10−3 T. (a) What is the largest force it can experience?

An ionized hydrogen atom (that is, a free proton) is moving through the magnetic field of the Milky Way galaxy, at a location distant from any star. The kinetic energy of the proton is 5.60 keV, and it moves through a circular path having a radius of 0.0317 astronomical units. An astronomical unit (AU) equals the average radius of the Earth's orbit around the Sun, 1.50×1011 m. What is the strength of the galactic magnetic field in this region of space?

Three parallel wires are arranged in a partial square configuration as shown in the diagram. In two of the wires, a 5.00×10−4 A current flows toward you, and in the third wire a 7.50×10−4 A current flows away from you. What is the strength of the magnetic field at the point P, at the "missing corner" of the square? (the 5A's are at opposite corners, the 7 and missing charges are at opposite corners to each other.)

Answer 1

3 questions in one post? A bit greedy, no?

#1 you need to use the Lorenz force equation:

http://en.wikipedia.org/wiki/Lorentz_for...

By moving through the potential difference, the particle gains an energy proportional to its charge and the potential difference. This manifests itself as kinetic energy, so once you know the energy gained, you can use:

Ek = (1/2) M V^2

to determine the velocity.

The force on a charged particle in a magnetic field depends on the angle between the velocity and the field, the charge, the magnitude of the velocity, and the field strength. You are given the charge and the field strength; you've computed the velocity; so you can choose the angle that gives the greatest force and compute the force.

#2 adds in the fact that the force exerted by a magnetic field is perpendicular to the velocity vector and the magnetic field itself. Therefore it causes the particle to move in a helix.

The force and the mass determine the angular acceleration and the velocity and radius are related to the angular acceleration by:

a = (v^2)/R

http://en.wikipedia.org/wiki/Centripetal...

#3 has nothing to do with the other two. The fact that you included it suggests that you haven't even thought about these questions.

In any case, the answer is here:

http://en.wikipedia.org/wiki/Biot-Savart...