1 .		The potential changes from 0V to 1V in the middle of the animation as shown by the equipotential lines.  The particle's velocity is displayed in meters/second.  Click-drag to place the 1 mC test charge anywhere in the animation before you press play.  You can also use the mouse to measure the potential at a point.  What is the mass of the particle? Start More Help: Show electric field. [Hint]   1 gram.   2 gram.   3 gram.   4 gram.
2 .		A 20 gr charged object is placed in a uniform electrostatic field. When the animation is running the object will begin to move and display  its velocity in meters/second. You can use the mouse to grab the charge while the simulation is running and while it is paused.  Imagine that you are actually dragging the object as you move the mouse. How much work is done dragging the charge from the blue line to the green line? start [Hint]   -1.5 J   -3 J   1.5 J   -1.7 J
3 .		The panel on the left displays an electric field plot.  The arrows in the field plot represent the direction and the colors represent the magnitude of the electric field.  Draw the equipotential lines for this field by dragging the pencil (at its tip) after clicking the "draw on" button. After you have drawn your lines, determine which potential plot best corresponds to your potential plot.   Start Field Potential A Potential B Potential C Potential D See how good your contour lines are by redrawing and after redraw, click to see the actual contours.  Enable Contour Lines on Click [Hint]   Field A.   Field B.   Field C.   Field D.
4 .		The panel on the left displays an electric field plot.  The arrows in the field plot represent the direction and the colors represent the magnitude of the electric field.  Draw the equipotential lines for this field by dragging the pencil (at its tip) after clicking the "draw on" button. After you have drawn your lines, determine which potential plot best corresponds to your potential plot. Start Field Potential A Potential B Potential C Potential D See how good your contour lines are by redrawing and after redraw, click to see the actual contours.  Enable Contour Lines on Click [Hint]   Field A.   Field B.   Field C.   Field D.
5 .		An equipotential plot is shown above.  How much work must an external force do in order to move an electron (the red object) from [x,y]=[1.1,-1.5] to [x,y]=[-1.6,1.2]?  The electric potential measured in Volts is shown next to the electron.  Start More Help: Show electric field. [Hint]   7 x 10 -21 Joule.   -7 x 10 -21 Joule.   3.5 x 10 -21 Joule.   0 Joule.
6 .		An equipotential plot is shown above.  How much work must an external force do in order to move an electron from [x,y]=[-0.5,-1.0] to [x,y]=[1.0,1.0].  Remember that you can measure the potential at any point by click-dragging the mouse.  Start More Help: Show electric field. [Hint]   -1.1 x 10 -20 Joule.   -5.8 x 10 -20 Joule.   -2.1 x 10 -19 Joule.   2.1 x 10 -19 Joule.
7 .		Equipotential lines around a point charge are shown above.  How much charge is located at the center?  You can measure the potential at any point by dragging the test charge around.   Distance is measured in m.   Start More Help: Show electric field. [Hint]   0.10 mC   0.15 mC   0.20 mC   0.25 mC
8 .		Two charged particles are shown with the charge on the right being 0.4mC.  Find the unknown charge on the left. You can measure the potential at any point by dragging the test charge around.   Distance is measured in m.  Start More Help: Show electric field. [Hint]   20  mC    0.25 mC   0.36  mC   0.4  mC
9 .		Four charges are shown (one is unknown) given in 10-10C that form what is known as a quadrupole.   Determine the charge of the unknown charge. You can measure the potential at any point by dragging the test charge around.   Distance is measured in m.  Start More Help: Show electric field. [Hint]   -0.5  mC.   0.5  mC.   0.25 mC.   1  mC.
10 .		The panel on the left displays an equipotential plot.  The contours represent points at the exact same potential.  Draw the electric field lines for this potential by dragging the pencil (at its tip) after clicking the "draw on" button. After you have drawn your lines, determine which field best corresponds to your potential plot. Start Potential Field A Field B Field C Field D See how good your field lines are by redrawing and after redraw, click to see the actual equipotential lines.  Enable Field Lines on Click  Note: There is a short delay between the "click" and the drawing of the field line.  [Hint]   Field A.   Field B.   Field C.   Field D.
11 .		The panel on the left displays an equipotential plot.  The contours represent points at the exact same potential.  Draw the electric field lines for this potential by dragging the pencil (at its tip) after clicking the "draw on" button. After you have drawn your lines, determine which field best corresponds to your potential plot. Start Potential Field A Field B Field C Field D See how good your field lines are by redrawing and after redraw, click to see the actual field lines.  Enable Field Lines on Click Note: There is a short delay between the "click" and the drawing of the field line.  [Hint]   Field A.   Field B.   Field C.   Field D.
12 .		Four simulations represent parallel plate capacitors. Which of the four capacitors would you expect the effect of fringing to be minimal, i.e. the capacitance is C=e0A/d? You can click-drag and observe the electric potential at that point.   Note: There is a 1-5% intrinsic error in the calculation of charge. Start Capacitor 1 Start Capacitor 2 Start Capacitor 3 Start Capacitor 4 [Hint]   All of the capacitors.   Capacitor 4 only.   Capacitors 3 and 4.
13 .		A capacitor depicted above is made of two charged plates each of surface area A=20cm2  (the plates are maintained at a constant voltage, the charge is given in fC (femtoCoulombs, 10-15 C), and distance is given in centimeters). Drag the blue capacitor plate into place 0.5 cm from the red plate. What happens to the total charge on the plates, and where does this charge come from? You can click-drag and observer the electric field at that point.  Note: There is a 1-5% intrinsic error in the calculation of charge. Start [Hint]   Increases. The charge comes from moving the plates together.   Decreases.   Increases. The charge comes from the battery that maintains the potential difference.
14 .		Two conducting plates are placed one above the other and connected to a battery as shown in the animation (charge given in mC and position given in centimeters).  The bottom  plate can be moved by click-dragging near the center of the plate. You can measure the voltage and the electric field at any point by click-dragging.  Note: There is a 1-5% intrinsic error in the calculation of charge. Which of the following statements is true?  Start More Help: Show electric field. [Hint]   The energy required to move an electron from the red plate to the blue plate does not depend on the position of the blue plate.   The electric field between the blue and red plates is independent of  the position of the blue plate.   The blue and red plates form a capacitor.  Their capacitance is independent of   the position of the blue plate.   The energy stored between the two plates is independent of  the position of the blue plate.
15 .		The two rectangles have uniform positive and negative charge densities (charge given in mC and position given in centimeters). Drag the bottom plate and observe the change in the potential energies of the plates. Why does the potential energy decrease when the plate separation decreases? You can measure the voltage at any point by click-dragging.  Note: There is a 1-5% intrinsic error in the calculation of charge.  Start [Hint]   The capacitance of the system decreases.   The potential difference between the plates decreases.   Positive work needs to be done on the system to create the charge separation and this energy is recovered by moving the plates closer together.