Phys102
Q1:
Term: 131
Online HW-Ch27-Lec02
A battery has an emf of 9 V and an internal resistance of 2Ω. If the potential
difference across its terminals is greater than 9 V:
A.
B.
C.
D.
E.
it must be connected across a large external resistance
it must be connected across a small external resistance
the current must be out of the positive terminal
the current must be out of the negative terminal
the current must be zero
Ans:
D
Q2:
A 0.20 A current flows through a metallic rod of length 1.0 m when connected to a
1.0 V battery. The rod is then cut into 4 identical pieces, which are then connected in
parallel to the same 1.0 V battery. The new current delivered by the battery is (Give
the answer in three significant figures and SI units)
Ans:
3R − 2(R + 10) = 0
3R − 2R − 20 = 0 ⇒ R = 20.0 Ω
ε − 3R = 0 ⇒ ε = 3R = 60 V
KFUPM-Physics Department
1
Phys102
Term: 131
Online HW-Ch27-Lec02
Q3:
The current in the R 2 -resisttor in the circuit shown is: (Give the answer in three
significant figures and SI units)
R1
12 V
R2
2R1
R3
R1
Ans:
12 V
2
R1
3
R1
E = I �2
I=
R2
R2
R1
+ R2�
3
E
R
�2 31 + R 2 �
2×6
+ 4 = 8rI = 12
3
I=
12
= 1.50 A
8
KFUPM-Physics Department
2