4. With the switch in the circuit of the top figure closed, there is no current in R2 because
the current has an alternate zero-resistance path through the switch. There is current in
Ri, and this current is measured with the ammeter (a device for measuring current) at
the bottom of the circuit. If the switch is opened (the bottom figure), there is current in
R2. What happens to the reading on the ammeter when the switch is opened?
a) The reading goes up.
b) The reading goes down.
c) The reading does not change.
5. The emf and the internal resistance of a battery are as shown in the figure. When the
terminal voltage Vab is equal to 17.4 V, what is the current through the battery,
including its direction?
a) 6.8 A, from a to b
b) 8.7 A, from b to a
c) 16 A, from b to a
d) 6.8 A, from b to a
e) 8.7 A, from a to b
31.0 V
2.0 Ω
b
6. For the circuit shown in the figure, write the Kirchhoff current equation for the node
labeled A. Notice the directions of the currents!
A
Ww
R
V
44
R
64
R
W
6
