EXAM 5
Partial credits were given with all the uncertainties interpreted in favor of students.
Any doubts, please ask me to show your exam.
Class2012
Rocket Exam1 Exam2 Exam3 Exam4 Exam4/curved Exam5
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Summer 2012. Exam 5, ##1,2
#1 A uniform electric field is directed out of page within a square shaped region of edge a.
The field magnitude is harmonically oscillating with frequency f and amplitude E. What is
the maximum induced magnetic field at a distance r =a/2 from the center of the square?
 Bds   
0 0
d
dE (t )
E (t )dA  B 2 (a / 2)   0 0 (a / 2) 2
,

dt
dt
dE (t )
 E  2fE.  B   0 0afE / 2
dt max
#2. A fish is 2 m below the surface of a smooth lake. What is the diameter of circle on the
surface through which the fish can see the world outside the water? (Use the refraction index
of water 1.33)
D / 2 H  tan( ),
sin( )  1 / 1.33
D  4.5m
Summer 2012. Exam 5, ##3,4
#3. Light intensity of a 100 W bulb at a certain distance is 1 W/m2. The distance is doubled.
What are the electric field amplitude and the magnetic field amplitude at that new distance?
2
2
I1  100W  I 2  I1 / 4  Erms
/ c 0  Emax
/ 2c 0
Emax  I1c 0 / 2 ,
H max  Emax / c
#4. Draw the principle rays
and the image of the object
presented by the fat arrow
given the diverging lens
focuses (dots)
1