Induced Current

Purpose: In our experiments, we take a look at the effects of the change in the magnetic field. We will find that there are a wide variety of applications with the change in magnetic field.

The Force On Two Wires With Current

We begin by looking at how the two wires with current generate a magnetic field and this magnetic field influences the two wires by providing a magnetic force. We see that force is very small.

Induced Current

We set up a couple a wires connected to a machine that detects current. These wires a oriented in a loop or loops and we put a magnet inside the loops. We see that is the magnet just sits there, there is not current in the wires.

Professor Mason shows us that when we actually move the magnet through the loops, current is generated. This means that the change in the magnetic field induces current along the wire. Professor Mason demonstrates to us that the direction the magnet is moving or changing determines which way the induces current flows. 

Induced Current On A Coil Of Wire

We begin to apply the idea of induced current in a way the would help us to power a light bulb without a power supply connected directly to the loop of wires connected to the light bulb. We connect an AC power supply to a loop of wires which generates a magnetic field though the center. Since we are using an AC power supply, the current is always change causing the magnetic field to always change. This is essentially the same idea s moving the magnet back and forth. If we place the loop of wires that are connected to the bulb where the magnetic field changes, we can, essentially, induce current to power the light bulb without wires.

Induced Current On Metal Rings

We take another look into the induced current idea but see how this works with a metal ring. We find that current is induced in the ring in a similar fashion as the loops of wire that are connected to the light bulb. The current induced is in the opposite direction as the current in the loops underneath the current in the wire and, thus, generates a magnetic field in the opposite direction. This is the same idea as putting the same poles of two magnets together. They end up repelling but since the coil of wires connected to the power supply is fixed on the ground, the ring is the only thing that moves and it makes sense that is should move up.

We write four things on our whiteboard that can induce current. We can change the speed on the moving magnet, change the radius of the loops, increase the size of the magnet, or change the length of the wire.

Magnetic Race

Professor Mason shows us that a magnet going through a metal tube will induce current in the metal tube which will then generate a magnetic field. This magnetic field slows the magnet down significantly.

On our white board, we draw a representation of what is happening as the magnet is falling through the metal tube. We, also, write up a theoretical equation of the induced emf.

Conclusion:  The change in the magnetic field has a lot of practical use. We find the we can induce current in a loop of wire which could, ultimately, power a light bulb or charge and object. We take a look at how the current can generate a magnetic field around the wires which in turn creates a magnetic force on the wire next to it. We discussed how the current in a loop of wire creates a magnetic field at the center of the loop directed perpendicular to the circular plane. This is why our metal rings flew up. Finally, we discussed how a magnet through a metal tube feels a magnetic force from the induce current on the tube that generates a magnetic field.