In this simulation, you can examine the magnetic field createdby the current in a solenoid, which is a cylindrical coil of wire.Instead of using a spiral-shaped coil, the simulation approximatesthe coil with a stack of seven single loops. The plane of each loopis parallel to the x-z plane, with a radius ofeither 60 cm or 25 cm, and the displayed field is in thex-y plane.

The parallel-plate capacitor is the standard way to create auniform electric field, while a current-carrying solenoid is agreat way to create a uniform magnetic field, although the electricfield is only perfectly uniform in the ideal case when the platesare infinitely large and the magnetic field is only perfectlyuniform in the ideal case when the solenoid is made from closelypacked loops that extend to infinity in the direction parallel tothe axis of the solenoid.

(a) Which of the following statements correctlycompare the ideal parallel-plate capacitor to the ideal solenoid?Select all that apply.

In the ideal capacitor changing the distance between the platesdoes not affect the electric field. In the ideal solenoid changingthe radius of the solenoid does not affect the magnetic field.

In both ideal devices the fields are uniform inside the devicesand zero outside.

A charged particle launched into the uniform field between theplates of the parallel-plate capacitor will follow a parabolicpath. The same is true for a charged particle launched into theuniform magnetic field inside the solenoid.

Doubling the magnitude of the charge on each plate of the idealcapacitor doubles the electric field. Doubling the current in eachloop of the solenoid doubles the magnetic field.

The electric field in the capacitor is produced by staticcharges, while the magnetic field in the solenoid is produced bymoving charges.

The direction of the uniform electric field in the capacitor isparallel to the plates making up the capacitor, while the directionof the uniform magnetic field is parallel to the axis of thesolenoid. b) Which of the following statements correctlydescribe what happens with the non-ideal solenoid shown in thesimulation? Select all that apply. Increasing the size of the loops making up the solenoidincreases the magnitude of the magnetic field at the center of thesolenoid. Staying inside the solenoid, the magnetic field generallydecreases in magnitude as you move away from the exact center ofthe solenoid along a direction perpendicular to the axis of thesolenoid (moving along the x-axis would be such adirection, for instance). Reversing the direction of the current without changing itsmagnitude results in the magnetic field reversing at every point,but no change in the magnitude of the field at any point. Increasing the separation between the coils of the solenoidincreases the magnitude of the magnetic field at the center of thesolenoid. As long as the current is non-zero, changing the magnitude ofthe current without changing its sign results in a change in themagnitude of the magnetic field at every point, but no change inthe direction of the field at any point. (Exceptions to this arepoints where the field is zero, which remain at zero.) The magnetic field generally decreases in magnitude as you moveaway from the exact center of the solenoid along the solenoid'saxis (the y-axis, in this case).