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Name: ________________________________________ Code # _________
Summer Session
2008
ID: X
1
UCSD Physics 2B
Practice Exam 5
Inductance & AC Circuits
READ ME !!!
Helpful Hints:
Do this exam a
few
times.
.. Once without the answers,
Once after seeing the solutions & Once again with your formula sheet
This is a good time to
add
formulas/constants to your sheet.
Remember, this is a
timed
exam.
.. work swiftly so you have time to check your answers.
1. How much does the
maximum emf
produced by a generator (a rotating coil) change if the
period
of
rotation is
doubled
?
A.
It is the same
B.
It is doubled
C.
It is quadrupled
D.
It is halved
E.
It is quartered
2. A 200turn coil is rotating in a magnetic field of magnitude
B
=
0.250
T
at a frequency of
f
=
60.0
Hz
.
The area of the coil
A
=
5.00
×
10
−
2
m
2
. What is the
maximum emf
in the coil?
A.
150 V
B.
450 V
C.
942 V
D.
240 V
3. The
rms
value of house voltage in much of Europe is 220 V. What is the
peak
voltage?
A.
440 V
B.
310 V
C.
220 V
D.
160 V
E.
120 V
4. If you plug a 1200W heater and a 600W toaster into 110V electrical outlets, what
total rms current
would these two appliances draw if the wiring is in parallel? (it always is!)
A.
5.45 A
B.
10.9 A
C.
11.6 A
D.
16.4 A
E.
23.1 A
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ID: A
2
5. If you
double
the
rms
voltage in an AC circuit, the
peak
voltage
A.
increases by a factor of 2
B.
decreases by a factor of 2
C.
increases by a factor of
2
D.
decreases by a factor of
2
E.
does not change
6. Your house is wired for
220 V
and you want to draw no more than
17 kW
. What circuit breaker do
you need in order
not
to shut off the power?
Note
: If circuit breakers are rated in 10A increments,
e.g., 10A, 20A, 30A, etc., you must choose one
just above
the value you calculate.
A.
20 A
B.
30 A
C.
40 A
D.
80 A
E.
150 A
7. A country house draws
52.3 A
with all its appliances running. A single highvoltage line delivers
power at
10,500 V
to a transformer on the pole which steps the voltage down to
117 V
for the house.
What is the
current in the highvoltage power line
?
Hint
: voltage and current may change, but power remains fixed.
A.
52.3 A
B.
583 mA
C.
11.1 mA
D.
4.69 kA
E.
none of these
8. The generators at a power plant operate at
1250 V
which is stepped
up
to
25,000 V
for transmission
. If the
primary
of the transformer has
500
windings,
how many windings
must the
secondary
have?
A.
25
B.
10,000
C.
62,500
D.
250
Name: ________________________
ID: A
3
9. In the circuit below, C = 0.13 mF and L = 270 mH. What is the
natural oscillation frequency
of the
circuit?
A.
2.85 x 10
4
rad/sec
B.
1.69 x 10
2
rad/sec
C.
5.93 x 10
3
rad/sec
D.
3.51 x 10
5
rad/sec
E.
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This note was uploaded on 08/23/2008 for the course PHYS 2b taught by Professor Schuller during the Summer '08 term at UCSD.
 Summer '08
 schuller
 Inductance

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