What is the function of the commutator in a motor?
a. it strengthens the magnetic field.
b. it changes the polarity of the magnet.
c. it causes the magnetic fields to interact.
d. it facilitates the movement of the current through a wire.

Two conductors, a and b, are each in the shape of a tetrahedron. but of different sizes. they are charged in the following manner: 1. tetrahedron a is charged from an electrostatic generator to charge q. 2. tetrahedron a is briefly touched to tetrahedron b. 3. steps 1 and 2 are repeated until the charge on tetrahedron b reaches a maximum value. if the charge on tetrahedron b was q/4 after the first time it touched tetrahedron a. what is the final charge qbmax on tetrahedron b?