How does an electroscope work in physics?
In physics, the electroscope is used to detect and measure charges that have been generated, for example, by friction. But how does it work?
What you need:
- For do-it-yourself:
- Jam jar with lid
- Copper wire
- Insulation (e.g. B. Plasticine or sealing wax)
- some silver paper
- Sample material (e.g. wool, comb, filler)
The electroscope in physics - a simple measuring instrument
- Electroscopes can be used in physics lessons, for example, to detect charges that flow from charged objects onto the measuring instrument. Objects charged in this way can be produced, for example, in special friction tests.
- The electroscope makes use of the fact that charges of the same name repel each other, and the greater the charge, the more so.
- The main component of an electroscope are therefore two leaves that are attached to a common metal rod in an (electrically) insulated container. Alternatively, this can also be a rotary pointer attached to a metal rod in the middle. In both cases, the metal rod - well insulated by plastic - leads to the outside.
- But how does it work? When touched, the charges not only flow to the upper part of the electroscope, but are also distributed Because of the good electrical conductivity of the metals, in principle on all parts, including the leaf respectively. the rotary pointer.
- Leaflets or Pointers now spread away from the rod, since both parts carry the same charge and consequently repel each other.
- The rash is greater, the more charge has been applied.
Electric charges can be detected with an electroscope. But how exactly ...
A DIY electroscope
In fact, an electroscope is one of the simplest measuring instruments one can find in physics (and thus also in school lessons) - electroscopes can even be made by yourself:
- Pierce the lid of the jar and put the copper wire through it, which you have provided with a slight bend at the bottom.
- Now isolate the wire from the lid, for example with plasticine, several layers of adhesive tape or the good old sealing wax.
- Cut an elongated strip from the silver paper and hang it folded over the copper bend - this part is the actual measuring instrument.
- Now load an item (e.g. B. a plastic comb or filler) by rubbing it with wool (or a cloth).
And this is how your self-construction works: Touch the charged object that protrudes from the glass Copper wire - the charges overflow and spread (electrical repulsion) the two parts of the strip apart. The higher the charge on the electroscope, the greater the effect.
You can "delete" the charge by hand - the charges flow off through your body.
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