Ill be needing switches which of the following

43. I’ll be needing Switches. Which of the following combinations of switches should be
closed so that the least current passes through the power supply?
A. S
1
and S
2
B. S
1
and S
3
C. S
2
and S
3
D. S
1
, S
2
, and S
3
Solution:
Least current corresponds to the largest value of equivalent resistance.
S
1
and S
2
closed: R
eq
= 11 . 87 Ω
S
1
and S
3
closed: R
eq
= 14 . 83 Ω
S
2
and S
3
closed: R
eq
= 13 Ω
S
1
, S
2
, and S
3
closed: R
eq
= 11 . 85 Ω
For the next two items, consider the circuit shown.
44. Junk Schon. Which of the following equations result from a correct application of Kirch-
hoff’s junction rule?
A – 23

Sample Exam Second Semester, AY 2016–2017 Physics 72
45. Looper. Which of the following equations result from a correct application of Kirchhoff’s
loop rule for the right inner loop?
A – 24