Ida Esther Irnanier, Age 10, Of Dallas, Tex.,for her question:
What is a leyden jar?
Electricity is one of our most useful servants, and we tend to take it for Granted. But our ancestors worked for ages to tame the mighty giant. The best brains Of many generations experimented and pondered over this mysterious force of Electricity. One of these early experiments led to the discovery of the leyden jar. A car ignition works with a gadget called a capacitor. Other capacitors work in Radio sets and television systems. The job of a capacitor is to store a charge of Electricity t0 be used when needed. All our different capacitors are descended from the leyden jar. It was the original gadget made to store a charge of electricity.
A leyden jar looks like a fruit jar with metal parts. It is lined half way with Tinfoil. Another layer of tinfoil. Reaches half way up the outside of the jar. The Top is sealed with a cork. This stopper is pierced with a brass rod with one end Reaching down into the jar and the opposite end poking up into the air. The strange gadget works because there are two kinds of electricity. We can Gather a charge of negative electricity or a charge of positive electricity. When we b ring the two opposite charges together, they spring into action.
Electricity is caused by teeming electrons hopping from atom to atom. Electrons pass freely through tin or copper, which are ca11ed conductor materials, but they cannot pass through glass, which is an insulator material. The leyden jar depends upon conductors and insulators. The glass insulator is sandwiched between layers of tin conductors.
The brass rod is also a conductor then connected to a battery, it conducts Electrons down into the jar. The tinfoil inside the jar then gains a charge of electricity. We can now charge the foil outside the jar. The two charges are Opposite, one positive and one negative. This variables the jar to store a larger amount of electricity.
A charge of electricity tries to escape by discharging itself. As the two charges build up in the leyden jar, they may discharge electric sparks. But some of the stored electricity can be used to give a spurt of energy to a battery or to do some other useful work.