A magnetic field is a vector that describes the magnetic influence of electrical charges that are in motion and in relation to magnetized materials. A galvanometer is an instrument for detecting and measuring high-speed electric current. One of the most common uses of a galvanometer is for analog measuring instruments, otherwise known as an ammeter, which is used to measure the flow of an electrical charge through an electrical circuit.
In this experiment, you will learn to make a DIY galvanometer which can be a fun science project for all ages.
Galvanometers allow us to do some really neat things. For example, laser beam shows, laser pointers, and laser projectors are all thanks to the science behind this instrument! Galvo systems are essentially mirrors that are moving on a technical system, which allow artists to time high-speed, laser lights alongside music.
Strip about an inch of the plastic insulation off each end of the wire, leaving bare copper wire exposed.
Then wrap the wire around the compass (from top to bottom where it wraps around the front). Wrap the wire tightly several times around the compass, leaving about eight inches of wire at each end.
Next, press the bare ends of the wire to a C- or D-cell battery. Only leave the circuit connected for 2-3 seconds, just long enough to see the needle start spinning. The current flow will heat the battery and wires if you leave them connected for more than a few seconds.
The current flowing through the circuit produces an electromagnetic field, like the Earth's magnetic field, which makes the magnetized compass needle try to align with it as the current moves through the circuit.
If you change the direction of the current (by turning the battery around so the negative terminal will connect to the other end of the wire), then you should also be able to see a change in the direction that the compass needle moves.
Try coiling your wire tighter, or make more coils around the compass. Does it make a difference in the amount of deflection or in how fast the compass needle moves? Does it make a difference if you have a moving coil?
This homemade galvanometer is not a quantifiable measure of current; it does not measure volts as a voltmeter would. Rather it shows you whether electrical current is flowing, and the direction it’s flowing in, but not how many amps are being produced.
Try testing for current from other sources.
Can you tell which direction it’s flowing? Did the lemon battery make the compass needle move more or less than when you hooked it to a regular battery?