Transcript To maximize the percentage of the power that is delivered from a

To maximize the percentage of the power from the
emf of a battery that is delivered to a device, what
should the internal resistance of the battery be?
1. It should be as low
as possible.
2. It should be as high
as possible.
3. The percentage
does not depend on
the internal
resistance.
With the switch in the circuit of Figure 28.4a closed, there is no current in R2
because the current has an alternate zero-resistance path through the switch.
There is current in R1, and this current is measured with the ammeter (a device
for measuring current) at the bottom of the circuit. If the switch is opened (Fig.
28.4b), there is current in R2. What happens to the reading on the ammeter
when the switch is opened?
Figure 28.4
1.
2.
3.
The reading goes up.
The reading goes down.
The reading does not
change.
With the switch in the circuit of Figure 28.8a open, there is no current in
R2. There is current in R1, however, and it is measured with the
ammeter at the right side of the circuit. If the switch is closed (Fig.
28.8b), there is current in R2. What happens to the reading on the
ammeter when the switch is closed?
Figure 28.8
1.
2.
3.
The reading increases.
The reading decreases.
The reading does not
change.
In Active Figure 28.3, a third resistor is added in series with
the first two. What happens to the current in the battery?
Figure 28.3
1. It increases
2. It decreases
3. It remains the same
In Active Figure 28.3, a third resistor is added in series with
the first two. What happens to the terminal voltage of the
battery?
Figure 28.3
1. It increases
2. It decreases
3. It remains the same
In Active Figure 28.5, a third resistor is added in parallel
with the first two. What happens to the current in the
battery?
Figure 28.5
1.
2.
3.
It increases
It decreases
It remains the same
In Active Figure 28.5, a third resistor is added in parallel
with the first two. What happens to the terminal voltage of
the battery?
Figure 28.5
1.
2.
3.
It increases
It decreases
It remains the same
Consider the circuit in Figure 28.18 and
assume the battery has no internal
resistance. Just after the switch is closed,
what is the current in the battery?
Figure 28.18
1.
2.
3.
4.
5.
0
.ε / 2R
.2ε / R
.ε / R
impossible to
determine
Consider the circuit in Figure 28.18 and
assume the battery has no internal
resistance. After a very long time, what is
the current in the battery?
Figure 28.18
1.
2.
3.
4.
5.
Mr W Hint: Try continuing this from the
previous problem (switch closed)
0
AND then try it with the switch open (as
.ε / 2R
shown)
.2ε / R
.ε / R
impossible to
determine