In the circuit shown, the galvanometer shows zero current. The value of resistance R is :  
A)  1 W
B)  2 W
C)  4 W
D)  9 W

Aprotein molecule in an electrophoresis gel has a negative charge.the exact charge depends on the ph of the solution, but 30 excesselectrons is typical. what is the magnitude of the electric forceon a protein with this charge in a 1500 n/c electric field?