Chapter 8 CQ and Quiz 8

• A loop of wire sits flat  on a horizontal surface in an area with uniform magnetic field directed vertically down. Magnetic field suddenly grows stronger. While magnetic field is changing, the induced current in the loop as viewed from above is:

  Counterclockwise
• A loop of wire lies flat on a horizontal surface. A bar magnet is held above with south pole pointing down. While bar magnet is held above the loop, the induced current in the loop as viewed from above is:

  zero
• Figure shows a square loop of a wire sliding into area of uniform in space and constant magnetic field. Loop slide with constant velocity. Pick the graph which best demonstrates dependence of magnetic flux though the loop on position:

  2; Trapezoid

  
• Taking counterclockwise direction of induced current as positive pick a graph which demonstrates the best dependence of induced current on position:

  3; negative, 0, then positive

  
• Figure shows the cross-section of cylindrical solenoid of radius R. Magnetic field created by solenoid is nearly uniform is space and decreases with time. Rank  the magnitude of electric fields of three points positioned at distance #1 R/2; #2 R and #3 2R  from the center, greatest first.

  2>1=3

  
• Figure shows the cross-section of cylindrical solenoid of radius R. Magnetic field created by solenoid is nearly uniform is space and decreases with time. Direction of induced electric field at distance 5R (yes, outside of solenoid)  is

  Counterclockwise

  
• Figure shows the straight wire carrying constant in time current I, The shown rectangular loop is moving down (towards the bottom of this screen) with constant velocity.  What is direction of induced  current is the loop?

  Clockwise
• A long wire carries current I in south direction. Positive charge Q moves parallel to the wire and west from the wire, towards south. Force exerted by charge on the wire is directed:

  West
• Figure shows two long straight wires with equal currents I perpendicular to each other. Current 1 is towards right, current 2 out of the page. Force exerted on wire 2 by wire 1  atthe closest point is

  Zero

  
• Wire with current carries current due north. A positive charge q is approaching this wire directly from the east. Force exerted by wire on the charge is directed:

  South
• Five wires carrying equal in magnitude currents are arranged first like it is shown in the line 1 of the picture, then like it is shown in the line #2 of the picture.  Distances between adjacent wires are all equal.  The net force acting on the central wire is measured for arrangement 1 (F1) and then for the arrangement 2 (F2). The ratio of magnitudes of these forces F1/F2 is

  1/3

  
• Two long wires oriented as shown in the picture are carrying equal in magnitude currents.  The net magnetic field at point P is directed:

  Up