Phys 313 Quiz 1

1. Vectors A = (3m, 1m) and B = (-2m, 2m). What is the cross product A x B ?

   Answer:   8m in the +z direction
          or
             8m k   (where "k" is the k-hat unit vector)
          or
             (0m, 0m, 8m)

2. Joe stands 1m from a a charge of +Q Coulombs. Which decreases the electric force on Joe by a larger amount?

a. changing the charge to +Q/3
b. increasing Joe's distance from the charge to 2m

   Answer: increasing the distance from the charge to 2m;
           the force between Joe and charge drops to 1/4 of its 
			  original value.

3. List

2 conducting materials
2 insulating materials
1 semiconducting material

   Answer: some good choices are
            conductors: gold, silver, iron, aluminum, copper
            insulators: rubber, glass, paper, cloth, wood
            semiconductors: silicon, germanium, gallium arsenide