One or more objects with uniform charge on them are located just off the screen on the left-hand side. Use the test charge to measure the electric field, and from that determine what type of object they are.
Mystery object 1

A single point charge. - Correct!
Two point charges.
A sheet of charge.
A line of charge.
X

Mystery object 2
Two point charges. - Correct!
A single point charge.
A sheet of charge.
A line of charge.
X

Mystery object 3
A single point charge.
Two point charges.
A line of charge. - Correct!
A sheet of charge.
X

Mystery object 4.
A sheet of charge. - Correct!
A single point charge.
Two point charges.
A line of charge.
X

Mystery object 5.
A sheet of charge.
Two point charges.
A single point charge.
A line of charge. - Correct!
X
 

Credits

Physlet problem authored by Scott Bonham.