ph106.q09.ch26.Capacitance                                                                            

 

   1     For a capacitor, the ...............   the area of opposite plates are and the ............ the

         distance between them the more charge is stored on its plates.

 

              A   larger,  smaller

              B    smaller, larger

              C   smaller, smaller

              D   larger, larger

 

   2     Three identical plate capacitors are set up.  The first has empty space between the plates.

         The second, air.  The third, has rubber.  When identical voltages are applied,  which has

         the most charge stored on the plates?

 

              A   The first.

              B    The second.

              C   The third.

              D   The charges are all the same.

 

   3     A parallel plate capacitor has circular plates whose radii are each 0.2m.  Find the

         capacitance if these plates are separated by 0.003 m of rubber.

 

              A   1.0x10^(-12) F

              B    1.0x10^(-11)F

              C   1.0x10^(-10)F

              D   1.0x10^(-9)F

 

   4     A camera flash unit capacitor has C=75 micro farads.  If 200 volts is applied to it, then the   energy stored is  ....

 

              A   15 J

              B    1.5 J

              C   0.15 J

              D   75 micro J

 

 

 

 

 

p106.q10.ch27.ElectricCurrent(Serway)                                                             

 

1            For a circuit with constant resistance, which graph represents the relation between current  and potential?

 

 

              A

 

 

 

 

              B

 

              C

 

              D

 

   2     The ratio of the potential difference across a conductor and the current moving through the  conductor is called the:

 

A    resistance.           B     conductance.    C  capacitance.          D   electric potential.

 

   3     The current through a conductor is 3.0 A when it is attached across a potential of 6.0 V.

         How much power is used?

 

A    0.50 W               B        2.0 W        C   9.0 W         D  18 W

 

 

   4     The current through a conductor is 3.0 A when it is attached across a potential of 6.0 V.

         What is the resistance of the circuit?

 

A      0.5 Ohms     B    18 Ohms     C  2 Ohms      D   6 Ohms

 

   5     What happens to the resistance, R,  of a wire if its cross-sectional area is doubled?

 

A     R is doubled.       B    R is halved.     C    R is quadrupled.     D    R is quartered.

 

 

p106q11.ch28.DCCircuit

 


   1     What is the current in the circuit shown right?

 

              A   0.5 A

              B    2.0 A

              C   6.0 A

              D   12 A

 

   2     What must be the reading in the ammeter A for the circuit section shown?

 

              A   0 A

              B    6.0 A

              C   8.0 A

              D   12A

 

   3     The capacitors (C1, C2, C3) are connected in parallel.  The equivalent capacitance of all

         these is .....

 

              A   C1xC2xC3

              B    1/C1 + 1/C2  + 1/C3

              C   C1 + C2 + C3

              D   1/(1/C1 + 1/C2 + 1/C3)

 

   4     In the circuit diagram, if R1=2.0 and R2=6.0 , what is the total resistance of the circuit?

A        1.5           B     4.0C    8.0          D      12

 

 

   5     A circuit is composed of a capacitor (C) and a resistor (R) in a series around a loop of wire

         with a switch which is initially open. If C=10-3 F and R=1000 Ohms, calculate the number

         of seconds after closing the switch at which the current will have decreased to 0.1 the

         initial current when first closed.

 

              A   46 s

              B    23 s

              C   2.3 s

              D   0.1 s

 

 

 

 

 

p106. q12. ch29. MagFieldForces

 

   1     The end of a small magnet is its north pole. If we suspend this magnet as a compass, this

         end will point to

 

              A   the earth's rotational (grid) north pole

              B    the earth's rotational (grid) south pole

              C   the earth's  magnetic pole NOT the rotational (grid) pole

 

   2     The lines of force of a bar magnet extend from ___________ pointing toward the

         ____________ of the bar

 

              A   one side of the bar to the other;  middle

              B    one pole to the other;  north pole

              C   one pole to the other;  south pole

                  

 

   3     A 0.5A electric current in a straight 0.1m wire goes into the page. Magnetic field lines

         extend downward on the page with a magnitude of 40T. The force due to the field on the

         wire is

 

              A   to the left

              B    to the right

              C   upward on the page

              D   downward on the page

              E    out of the page toward you

 

   4     A 0.5A electric current in a straight 0.1m wire goes into the page. Magnetic field lines

         extend downward on the page with a magnitude of 40T. The magnitude of the force due to the field on the wire is

 

              A   1 N

              B    2 N

              C   3 N

              D   4 N

              E    5 N

 

 

 

p106. q13. ch30. Magnetic Field Sources

                                                                                                                     

   1     A straight wire carries a current of 16A. What is the magnitude of the magnetic field

         created by this wire at a perpendicular distance of 35cm from the wire?

 

              A   9.1 x 10-6 T

              B    8.1 x 10-6 T

              C   7.1 x 10-6 T

              D   6.1 x 10-6 T

              E    5.1 x 10-6 T

 

   2     Two straight wires which are parallel to one another each carry a current of 16A. The two

         currents are, however, in opposite directions to one another. What are the directions of the

         forces on the wires created (ultimately) by these two currents?

 

              A   directly towards one another.

              B    directly away from one another.

              C   one toward the other but the other away.

              D   90 degrees to the line between them.

              E    in opposite directions but along the directions of the wires.

 

   3     A long solenoid has 5000 turns per meter and carries a current of 20A. What is the

         magnetic field inside the solenoid?

 

              A   132T

              B    15T

              C   1.3T

              D   0.126T

              E    0.01T

 

4            According to Ampere's law, an integral around an imaginary closed loop

  (    ∫ B. ds =  µo  Itotal  where Itotal  is the total current passing  along wires passing through the middle of  the loop. Here B is the magnetic field vector due to the current in the wires and ds is thei ncremental arc vector  along the loop.  Imagine a wire with a circular loop 90 degrees to it     at a distance r from it.  The current I in the wire makes a magnetic field circularly  symmetric with the field lines extending along the loop.  Which answer below gives

Ampere's law around this loop?  You can calculate the field strength as a function of  r andI from this equation.

 

              A   pix r^2 x B = I

              B    pi x r x B=  µo x I

              C   pi x r x B =  µo x I^2

              D   2x pi x r x B =  µo x I