Scroll over the image below to hear music produced by an electric guitar.

The sound produced by an electric guitar depends on the principles of electromagnetic induction. The body of the guitar contains one or more electromagnets–called pickups–that sit directly under the strings. As the steel strings move through the magnetic field created by these pickups, they induce an electric current, which is carried to the amplifier. Since the strings vibrate with a specific frequency, the current carried to the amplifier has the same frequency. The speaker in the amplifier matches this, and you hear a note with a pitch that matches the frequency of vibration of the string.

In this section, you will investigate electormagnetic induction and how it is used in everyday life.

You have just seen that electric current causes a magnetic field. It turns out that the opposite is true as well. Changing a magnetic field around a loop of wire will create a current. In the following simulation, you will investigate the use of a magnet to induce a current in a wire loop. Answer the questions that follow.

Click the "Pickup Coil" tab at the top of the simulation window. Use the mouse to move the magnet around the simulation window.

How does the light bulb react when you move the magnet up and down?

Interactive popup. Assistance may be required.

The bulb does not react.

How does the light bulb react when you move the magnet to the left or right, but not through the loops?

Interactive popup. Assistance may be required.

The bulb lights, but very dimly.

How does the light bulb react when you move the magnet to the left or right through the loops?

Interactive popup. Assistance may be required.

The bulb lights brightly.

How does the number of loops affect the brightness of the bulb?

Interactive popup. Assistance may be required.

The more loops, the brighter the bulb lights.

Just as magnets exert forces on one another, they exert forces on wires that carry a current. In the following video, you will see the effect that a magnetic field has on a current carrying wire.

Physics - Understanding Electromagnetic induction (EMI) and electromagnetic force (EMF) - Physics, Elearnin, YouTube

Describe in your own words the relationship between the electric and magnetic fields as seen in the investigation you just completed.

Interactive popup. Assistance may be required.

The current carried through the wire has an electrical field. This interacts with the magnetic field creating electromagnetic induction.

Sources used for this section as they appear, top to bottom:
• Guitar image: Fender Guitar, Wickler, Wikimedia Commons
• Guitar audio: Guitar with fuzz, Deltabeignet, Wikimedia Commons
• String animation: Single coil string anim., DAKE, Wikimedia Commons
• Magnet simulation: Generator, University of Colorado – Physics
• Magnetic field activiy: Physics - Understanding Electromagnetic induction (EMI) and electromagnetic force (EMF) - Physics, elearnin, YouTube