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THE IUG
DATE:5-6-2007
PHYSB 1301
FINAL EXAM.
.……… ………:‫المدرس‬
……………:‫الرقم الجامعي‬
Part I
DEPT. OF PHYSICS
TIME:1-Hr
.……… ………………:‫اسم الطـالب‬
Part II
Q1
Q2
Total
Q3
Q4
PART I: choose the correct answer
1) Object A has a charge Q and object B has a charge 3Q. Which of the following is correct
a) ) FAB =3 FBA
b) FAB =-3 FBA
c) FAB = FBA
d) FAB =- FBA
c) A/m
d) non of the them
2) The unit of N/C is equivalent to
a) V/m
b) V.m
q1
3) Three point charges lie along the x-axis.
For q1 to be in equilibrium
a) q3  4q2
b) q3  4q2
q2
q3
d
c) q3  2q2
d
d) q3  2q 2
p
4) Two similar positive charges are arranged as shown.
The direction of the electric field at point p is
d
a) up
c) left
d
b) down
d) right
Q
d
Q
5) A solid conducting sphere has charge Q. The charge density of the sphere has a unit of
a) C
b) C/m
c) C/m2
d) C/m3
6) A closed box with no charge inside is placed in an electric field E. For the total flux to be zero
through the surface of the box
a) E must be uniform
c) the box must be oriented in a certain way
b) the box must be symmetric
d) always
7) The unit of the electric flux is
a) V.m
b) N.m/C
c) N/m.C
d) V/m
2
8) Two points A and B are located in a uniform electric filed directed as
shown. The potential difference V  VB V A is
a) positive
b) negative
c) zero
B
A
d) we need more informatiom to know
9) A point charge of 2Q is at the center of a conducting spherical shell. The net
charge on the shell is Q. The charge on the inner surface of the shell is
a) 2Q
b) 3Q
c) -2Q
2Q
Q
d) Q
10) Refering to the previous question, the charge on the outer surface of the shell is
a) 2Q
b) 3Q
c) -2Q
d) Q
11) A system of two point charges q1 and q2 with distance r between them. The potential energy of
the system is
a)
Kq1q 2
r
2
b)
K q1 q 2
r
c)
2
Kq1q 2
r
d)
K q1 q 2
r
a) 4 F
b) 8 F
c) 2 F
4 F
4 F
12) For the capacitor combination shown, the equivalent capacitance is
d) 0.5 F
4 F
13) Considering the circuit shown, if the charge on the 4-F capacitor is 8 C,
the charge on the 2-F capacitor is
a) 8 C
b) 4 C
c) 16 C
2 F
3 F
d) 2 C
14) The unit of the resistivity  is
a) .m
b) /m
c) (.m)-1
d) .m2
15) Three 10- resistors are connected as shown. The maximum power
that can safely be delivered to any single resistor is 40 W. The current
in R1 is
10 
R1= 10 
10 
a) 4 A
b) 1 A
c) 6 A
d) 2 A
3
16) Consider the circuit shown. Just after the switch is closed (t=0), the
current I is
C
I

a)

2R
b)
2
R
c)

R
4
F
R
R
d) zero
17) Refering to the previous question, after a very long time (t ) the current I is
a)

2R
b)
2
R
c)

R
d) zero
18) A charged particle moves with velocity v in a magnetic field B. The magnetic force on the
particle is maximum when v is
a) parallel to B
b) antiparallel with B c) perpendicular to B
d) zero
19) The figure shows three long parallel wires with identical currents.
The net magnetic force on the middle wire is directed
I
d
I
2d
a) out of page
b) into page
c) up
I
d) down
20) The unit of  o is
a) T
b) N/A2
c) ) kg.A/m
d) T.m/A
21) A circular loop of wire with radius 20 cm and carries a current of 2 A
clockwise as shown. The magnetic dipole moment of the loop is
a) 0.25 A.m2 
b) 0.25 A.m2 O
c) ) 25 A.m2 
2A
20 cm
d) 25 A.m2 O
22) The magnrtic filed lines produced by a straight wire carrying a current are
a) in the direction of the current
c) circles concentric with the current
b) opposite to the direction of the current
d) non of them
4
23) In Ampere's law,
a) any surface
 B  ds   o I , the integration must be over
b) any closed surface
c) any path
d) any closed path
24) A very long wire has a current I direct into the page as shown. The direction
of the magnetic filed at point p is
a) to the right
b) to the left
c) up
I
p
d) down
25) The magnetic flux through any closed surface depends on
a) the poles inside the surface
c) the size of the surface
b) the magnetic filed lines penetrating the surface
d) always zero
26) The time constant of the RL circuit is given by
a) L R
b) R L
c) LR
d)
27) The figure shows a rectangular loop moves at constant velocity
through a region of uniform magnetic field directed out of the
page. At which of the three indicated loop positions is the
current induced in the loop is counterclockwise
a) the left
b) the right
c) the middle
1
2
LR
 




d) the left and the right
28) In the circuit shown, the switch is closed for a long time.
the maximum energy stored in the inductor is
100 
50 V
a) 0.25 J
b) 0.5 J
c) 1 J
v
2H
d) 4 J
29) Refering to the previous question, the switch is now opened. The maximum energy stored in the
capacitor is
a) 0.25 J
b) 0.5 J
c) 1 J
d) 4 J
30) Refering to the previous question, the switch is now opened. The frequency of the oscillation is
a) 2.83 mHz
b) 0.35 mHz
c) 2.83 Hz
d) 0.35 Hz
5
PART II: Solve the following problems
R1=8 
Q1) In the circuit shown, find the maximum
charge on the capacitor.
30 V
3 F
R2=6 
R3=4
20 V
6
Q2) A very long wire of radius R has a current I that is uniformly distributed through
R
the wire.
a) Find the magnetic field at a point inside the wire (r > R)
I
b) Find the magnetic field at a point inside the wire (r < R)
7
Q3) The figure shows a cross-section of an ideal solenoid bounded by a
square wire of side d.and resistance R The radius of the solenoid is R and
its current varies with time according to I   t   with  and  are
positive constants. Find the induced current in the square loop and
indicate its diredtion
d
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R
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8
Q4) Consider thr RL circuit shown.
S
a) Find the current in R1 immediately after
closing S (at t=0)
80 V
R1=4 
R2=6 
b) Find the potential difference across L a long time after closing S (at t )
2H
R3=8