1) A charge of +0.06 C resides on an electrical component of a computer.  A distance 2 cm away a second component has a charge of +0.08 C.
 a) What will be the electric field at a point in a cpu chip located exactly halfway between the two point charges?
 b) What will be the electrical force acting on each charge?

2) The electrons in a beam inside a TV set have a velocity of 1x107 m/s. Suppose these electrons are traveling North (they go from the back of the tube to the front). An electric field inside the tube is used to bend the path of the beam. The electric field is pointing West and has a magnitude of 100N/C.          me = 9.11x10-31 kg        e = 1.6x10-19 C
a)  Carefully draw a picture indicating the approximate path the electrons will take when the field is turned on (assuming they still hit the screen at the front of the set).
b)What will be the acceleration of the electron due to the electric field?
c) Assume North is the y-direction and East is the x-direction. What are the x and y velocities after 5x10-7 s?
d) What magnitude of magnetic field inside the TV would exactly compensate for the electric field so that the electron goes straight through with a velocity of 1x107 m/s and hits the screen without bending?
e) Redraw the picture you drew in part a) and include the orientation of the magnetic field which would compensate for the electric field.

3) Suppose the linear charge density on a nerve axon (cylindrical in shape with radius 0.002m) is given by    l =  5  C/m .
a) Calculate the total charge on the axon for a length of 0.3m.
b) Use Gauss' Law to find the electric field as a function of r outside the axon .

4) You are doing a biology experiment to determine whether ducks navigate using the earth's magnetic field or not. To counteract the earth's magnetic field you use 100 turns of wire in a circular coil of radius 0.08 m. Assume the coil is in the plane of the table. The field at the center or the coil is given by B = mom/2p a3 where a is the coil radius.
a) What magnetic moment is needed to equal the earth's field of 3x10-5 T at the center of the coil?
b) What current is needed to equal the earth's field of 3x10-5 T at the center of the coil?
c)  Looking down onto the coil, which direction must the current flow (the created field must point upwards to counteract the earth's field which points down)?
d) Use the Biot-Savart law to derive the expression for the field shown above for a point at the center of the coil.

5) Suppose the nerve axon mentioned in 3) is now carrying a current of I = .02 A (instead of a static linear charge) which is uniformly distributed inside the axon (this is not entirely accurate but can be used as an approximation). Assume, again, that the axon is cylindrical in shape with radius 0.002m.
a) What current density (current per area) flows in the axon?
b) Use Ampere's law to find the magnetic field outside the axon.
c) Use Ampere's law to find the magnetic field inside the axon.

Bonus:
a) How does a cathode ray tube work?

b) What is a cyclotron?