Download HW14 - University of St. Thomas

Physics 112 HW14
Due Wednesday, 15 October 2014
/6
P04. A light bulb (resistance > 0) is connected to an ideal voltage source
(negligible internal resistance). The light bulb, of course, goes on.
a) As the bulb heats up, its resistance increases. Does this make the bulb brighter,
dimmer, or just as bright as when it first went on? Why?
b) Add another bulb in series with the first bulb. Will the bulbs be brighter, dimmer,
or just as bright as the first bulb alone? Why?
c) Remove the 2nd bulb in series, and instead connect it in parallel with the first bulb.
Will the bulbs be brighter, dimmer, or just as bright as the first bulb alone? Why?
VIR01. The circuit at left consists of two
4.00 V
batteries (the grey shaded areas) broken up
into ideal EMF sources with internal
c 9.00 Ω
b 0.50 Ω
resistances, along with two resistors.
d
a) What is the voltage difference 6.00 Ω
between points a and d?
0.50 Ω
a
8.00 Ω
b) What is the terminal voltage across
the 4 V battery? (What is the voltage
8.00 V
one would measure across it when it
is put in this circuit, or the voltage between points b and c?)
c) A battery with EMF 10.30 V and internal resistance 0.50 Ω is inserted at point d
in such a way that its negative terminal (the box) is connected to the negative
terminal of the 8.0V battery. What is the terminal voltage across the 4 V battery
now?
ER01. Each resistor in the circuit at left has
10Ω.
a) Calculate the equivalent resistance
a
between points a and b.
A 100V battery is now connected across
points a and b.
b) How much current comes out of the
battery?
c) What is the voltage across and current through the bottom-most resistor?
ER02. If an ohmmeter is connected between points a and b in each of the circuits below,
what will it read?
a)
a
100Ω
b
b)
7Ω
a
10Ω
50Ω
60Ω
75Ω
40Ω
25Ω
30Ω
20Ω
50Ω
(over)
45Ω
b
b
2.00 Ω
K01. In the circuit at right, find the current through and the
voltage across each resistor. Also calculate the voltage
difference between points a and b.
10.00 V
1.00 Ω
3.00 Ω
a
5.00 V
b
4.00 Ω
10.00 Ω
K03. (Wolfson, Ch. 25 Problem 53) In the figure at right, find the current through R and
give its direction.
270Ω
820Ω
R
6V
4.5V
1.5 V
150Ω
(over)