Download PHY 132–1E2 - Oakton Community College

PHY 132–1E2
Oakton Community College
Summer 2008
Practice Test 3
Ten questions
Useful formulas:

 
F  qv  B
B 

B
loop



  B
 = NIABsin
   N ddtB
M
U


 E l  
||
loop
N 2 B2 N1 B1

i1
i2
1 2
Li
2
I rms 
I
V = IZ
R
Z
Bwire 
d B
dt
 2  M didt1
B2
B2

2 2 K m  0
Vrms 
2
series L-R-C:
cos  
u
V
2


 

F  Il  B
 B  dA  0
 A
0 I
2r
Bsolenoid 


  
F  q E vB
l
L
R
p = vi
vL  L
i L
t
1
LC
0 
VL  IX L  IL
VR  IR
0 I enclosed
v C
t
N B
i
1 

Z  R 2   X L  X C 2  R 2  L 

C 

Vrms = IrmsZ
||
loop
iC  C
L


 B l  
  0 nI

1  M didt2

 0 NI
VC  IX C 
2
tan  
V2 N 2

V1 N1
Pav = VrmsIrmscos
I
C
XL  XC
R
V1I1 = V2I2
Sinusoidal waves:
+x direction:
  x 
  x 
  x t 
yx, t   A cos   t   A cos2f   t   A cos2     A coskx  t 
  v 
  v 
   T 
–x direction:
  x 
  x 
  x t 
yx, t   A cos   t   A cos2f   t   A cos2     A coskx  t 
  v 
  v 
   T 
Electromagnetic Waves:
E = cB
c
1
 00
v
1


c
KK m

c
n
n  KK m
1 of 7
PHY 132–1E2
Oakton Community College
Summer 2008
Practice Test 3
Useful formulas:
u
1
1
0E2 
B2  0E2
2
2 0
I  Sav 
S   0 cE 2 

1  
S
EB
EB
0
0
Emax Bmax Emax 2 1   0 
1


Emax 2   0 cEmax 2


2 0
2 0 c 2   0 
2
Flow rate of momentum:
1 nm = 10–9 m
1 dp S EB
 
A dt c 0c
1 µm = 10–6 m
me = 9.11 × 10–31 kg
1 pF = 10–12 F
mp = 1.67 × 10–27 kg
c ≡ 299,792,458 m/s
0 = 8.854 × 10–12 F/m
k
1
4 0
 8.988 10 9
e = 1.602 × 10–19 C
Nm 2
C
2
 0  4 10 7
Tm
A
2 of 7
PHY 132–1E2
Oakton Community College
Summer 2008
Practice Test 3
1) A beam of singly ionized sodium ions (Na+) is created by accelerating them from rest through a voltage
of 250 V. The beam then enters a region with a constant magnetic field B = 2.30 T that is directed
perpendicular to the beam. What is the radius of the circular path the beam takes? The mass of a sodium ion
is m = 3.817 × 10–26 kg.
2) If an electric field were to be directed perpendicular to both the incoming beam and the magnetic field of
problem 1 to make a velocity selector, what would the magnitude of the electric field be if the sodium ions
are to pass undeviated?
3 of 7
PHY 132–1E2
Oakton Community College
Summer 2008
Practice Test 3
3) A wire loop of radius r = 2.00 mm has 80 turns, and 2.00 A of current is flowing through it. What is the
maximum possible value of the torque that a magnetic field B = 2.50 T can exert on the loop?
4) A long straight wire with diameter d = 0.500 mm carries a current of 5.00 A. What is the magnitude of
the magnetic field due to that current at a point a) 0.500 mm from the center line of the wire b) 5.00 mm
from the center line of the wire?
4 of 7
PHY 132–1E2
Oakton Community College
Summer 2008
Practice Test 3
5) A wire coil of negligible resistance has 1000 turns and has a diameter of 6.00 cm. A 1.00 k resistor is
connected to the coil. A uniform, time-varying magnetic field exists inside the coil, and is given by:
B(t) = (2.50 × 10–5 T)cos[(377rad/s)t]. What is the magnitude of the maximum current in the resistor?
6) For the coil of problem 5, determine the self-inductance, L, of the coil. (N = 1000, a = 3.00 cm)
5 of 7
PHY 132–1E2
Oakton Community College
Summer 2008
Practice Test 3
7) The circuit shown has an input voltage of 5.00 Vrms, and the frequency of the sinusoidal voltage is
60.0 Hz. a) Calculate XC, XL and Z. b) Calculate the rms current and the average power delivered.
300 
5.0 V
10.6 µF
0.250 H
8) For the transformer circuit shown below, the input voltage is 120 V rms at 60 Hz. There are 2400 turns in
the primary winding, and 100 turns in the secondary winding. a) What is the rms current through the
resistor? b) What is the rms current delvered by the source?
24:1
120 V
1.0 k
6 of 7
PHY 132–1E2
Oakton Community College
Summer 2008
Practice Test 3

9) An electromagnetic plane wave has an electric field of the form: E  xˆ E0 coskz  t  . Its frequency is

830 kHz, and E0 = 0.0145 V/m. The magnetic field for the wave has the form: B  uˆ B0 coskz  t  , where
B0 has a positive value. a) In which direction is this wave traveling? b) What is the wavelength of this wave
in a vacuum?
10) For the wave of problem 9, a) What is the value of B0? b) The unit vector, û , is which of the following:
x̂ ,  x̂ , ŷ ,  ŷ , ẑ , or  ẑ ?
7 of 7