Download Final Review

Final Review
PHYS 212
Chapter 21
36.(II) Two point charges Q1=-25µC, and Q2=+45µC
are separated by a distance of 12 cm. The electric
field at the point P (see Fig. 21–58) is zero. How far
from Q1 is P?
Chapter 22
27. (II) Two thin concentric spherical shells of radii
r1
and
r2
 r1 < r2 
contain uniform surface
charge densities
and
respectively (see Fig. 22–31). Determine the electric field for (a)
0 < r < r1 , (b) r1 < r < r2 , and (c) r > r2 . (d) Under what conditions will E  0 for r > r2 ? (e)
r < r < r2 ?
Under what conditions will E  0 for 1
Neglect the thickness of the shells.
Chapter 22
34. (II) A very long solid non-conducting cylinder of
radius R0 and length l0(R0≪ l0) possesses a uniform
volume charge density 𝜌𝐸 (C/cm3), Fig. 22–34.
Determine the electric field at points (a) outside the
cylinder (R› R0) and (b) inside the cylinder (R‹ R0). Do
only for points far from the ends and for which R≪ l.
Chapter 24
30.(II) Suppose in Fig. 24–23 that C1=C2=C3=16µF and C4=28.5µF.
If the charge on C2 is Q2=12.4µC, determine the charge on each
of the other capacitors, the voltage across each capacitor, and
the voltage Vab across the entire combination.
Chapter 24
59.
(II) Two different dielectrics each fill half the space
between the plates of a parallel-plate capacitor as shown in Fig.
24–30. Determine a formula for the capacitance in terms of k1,k2
,the area A of the plates, and the separation d. [Hint: Can you
consider this capacitor as two capacitors in series or in parallel?]
Chapter 24
62. (II) Two identical capacitors are connected in parallel
and each acquires a charge Q0 when connected to a source
of voltage V0 . The voltage source is disconnected and
then a dielectric (K=3.2) is inserted to fill the space
between the plates of one of the capacitors. Determine (a)
the charge now on each capacitor, and (b) the voltage now
across each capacitor.
Chapter 26
25. (III) Consider the network of resistors shown in Fig. 26–43. Answer qualitatively:
(a) What happens to the voltage across each resistor when the switch S is closed? (b)
What happens to the current through each when the switch is closed? (c) What happens
to the power output of the battery when the switch is closed? (d) Let R1=R2=R3=R4=
125Ω and V= 22.0V. Determine the current through each resistor before and after
closing the switch. Are your qualitative predictions confirmed?
Chapter 26
48.(II) The RC circuit of Fig. 26–59 (same as Fig. 26–18a)
has R=8.7kΩ and C=3.0μF. The capacitor is at voltage V0
at t=0 s when the switch is closed. How long does it take
the capacitor to discharge to 0.10% of its initial voltage?
Chapter 27
19. (II) A doubly charged helium atom whose mass is 6.6 X 10-27 kg
is accelerated by a voltage of 2700 V. (a) What will be its radius of
curvature if it moves in a plane perpendicular to a uniform 0.340-T
field? (b) What is its period of revolution?
Chapter 27
25. (II) A proton moves through a region of space where there is a magnetic field




B  0.45 ˆi  0.38 ˆj T and an electric field E  3.0 ˆi  4.2 ˆj 3 103 V/m. At a given instant,


the proton’s velocity is v  6.0 ˆi  3.0 ˆj  5.0 kˆ 3 103 m/s.
Determine the components of the total force on the proton.
Chapter 28
21. (II) Two long wires are oriented so that they are perpendicular
to each other. At their closest, they are 20.0 cm apart (Fig. 28–
39). What is the magnitude of the magnetic field at a point midway
between them if the top one carries a current of 20.0 A and the
bottom one carries 12.0 A?
Chapter 28
35. (II) A circular conducting ring of radius R is connected to two
exterior straight wires at two ends of a diameter (Fig. 28–44).
The current I splits into unequal portions (as shown) while passing
through the ring. What is at the center of the ring?