Questions 37-38:
37. If the ammeter in the circuit above reads zero, what is the resistance R ?
(A) 1.5Ω
(B) 2Ω
(C) 4Ω
(D) 6Ω
38. If the current through the ammeter is to flow toward the bottom of the page, how must the resistance R compare to the value found in \#37?
(A) it must be larger, so that the voltage across R increases
(B) it must be larger, so that the equivalent resistance of the circuit increases
(C) it must be smaller, so that the voltage across R decreases
(D) it must be smaller, so that the equivalent resistance of the circuit decreases