Download Exam2a Solutions

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If &= 9.0 V, what is the current in the 15-R resistor?
F
a. O.1OA
b. 0.15A
Fw-
15 R
E
e. 0.30 A
-111
A circuit contains a 6.0-V battery, a 4.042 resistor, a 0.60-pF capacitor, an
ammeter, and a switch in series. What will be the charge on the capacitor long
-safter the switch is closed?
zero
b. 0.10 pC
Q. 3.6*u
d. 2.4 pC
e. 6.0 pC
4.0
a.
6V 4
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3'6FC
OV6 pF
Q=cv -
o,6rf
3. What is the equivalent resistance between points a and b?
L ~ ~ l=
f s
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4. Three resistors connected in series each carry currents labeled 11,I2 and 13.Which
of the following expresses the value of the total current IT in the system made up
of the three resistors in series?
5. There is a current I flowing in a clockwise direction in a square loop of wire that
is in the plane of the paper. If the magnetic field B is toward the right, and if each
side of the loop has length L, then the net magnetic torq_ue acting on the loop is:
e. zero
J-3
L
T = BIT4
6. Two parallel conductors each of 0.50 m length, separated by 5.0 x
m and
carrying 3.0 A in opposite directions, will experience what type and magnitude of
mutual force? (magnetic permeability in empty space po = 47r x lo-' T d A )
=?!==
a.
b.
c.
d.
e.
I
F
attractive, 0.06 x 1o - N
~
repulsive, 0.60 x
N
attractive, 1.8 x
N
repulsive, 1.8 x 10-4 N
zero
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7. A solenoid with 500 turns, 0.10 m long, carrying a current of 4.0 A and with a
radius of
m will have what strengthk-]at
its center? (magnetic
T-dA)
permeability in empty space po = 4 n x
8. An electron moves through a region of crossed electric and magnetic fields. The
electric field E = 2000 V/m and is directed straight down. The magnetic field B =
0.80 T and is directed to the left. For what F m 2 o f the electron into the paper
will the electric force exactly cancel the magnetic force?
9. At what speed rshould the bar in the figure be moved to produce a current of 1A
in the resistor? Assume B = 1.50 T into the page, R = 12.0 Q and the length of
the bar is 4.50 m.
10. By what factor is the self-inductance of an air solenoid changed if its length and
number of coil turns are both tripled?
which a 200-turn, flat coil of cross sectional
What is the minimumlf=dwith
area 300 cm2 can be rotated in a uniform 30-mT magnetic field if the maximum
value of the induced emf is to equal 8.0 V?
&*P
k *--e
.f= .
f hw
2 r NAB
--
27.0 v
21t (2#v)(~?](308$$
= 7,/
ti2
_____C_
12. A uniform 4.5-T magnetic field passes through the plane of a wire loop 0.10 m2 in
area. What flux passes through the loop when the direction of the 4.5-T field is at
a 30' angle to the normal of the loop plane?
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