Electroscope?

Question

I think I know the basics of the electroscope, but I am still not confident. What is the difference when a negatively charged rod is held close to versus actually touching the metal head of the electrscope? In general, the positive charges would be attracted to the negative rod, while the negative charges on the electroscope would repel, thus making the gold leaf rise, right? And oppositely, if a positively charged rod is placed close to the metal head of an electroscope, then the electrons would be attracted, while the positive charge would make the leaf rise? Is this correct? Any advice would be appreciated... Thanks

Answer 1

You are correct. A rod of either charge produces the same result. The only difference between bringing the rod close and actually touching is that after touching, the electroscope remains charged and the leaves stay lifted. (Charge is transferred to the leaves.) If the rod merely comes close, the electoscope is charged only when the rod is near, and the leaves will fall when the rod is removed. (Charge on the electroscope is merely separated, one charge remaining on the leaves, and an opposite charge on the metal head; when the charged rod is removed, the separated charges rejoin.)

Answer 2

The gold-leaf electroscope was one of the first instruments to indicate electric charge. It is still used for science demonstrations but has been superseded in most applications by electronic measuring instruments. The instrument consists of two thin leaves of foil suspended from an electrode. When the electrode is charged by induction or by contact, the leaves acquire similar electric charges and repel each other due to the Coulomb force. Their separation is a direct indication of the net charge stored on them. The leaves may be enclosed in a glass envelope to protect them from draughts, and the envelope may be evacuated to minimize charge leakage. A further cause of charge leakage is ionizing radiation, so to prevent this, the electrometer must be surrounded by lead shielding. It should be noted that this type of electroscope purely acts as an indicator and not a measuring device. The Braun electroscope replaced the gold-leaf electroscope for more accurate measurements.

Another way to construct an electrometer is to suspend two aluminum or copper foil pieces on wire (tantalum or platinum is best), or (far less expensively) nylon monofilament. The most common radiation measurement device, and widely used in the nuclear industry, the Quartz Fibre Electrometer (or QFE) personal dosimeter, is actually a ruggedized, calibrated electroscope. This uses the leakage effect mentioned above to detect ionising radiation.

Here... it may help you have confidence of your answer.....

Answer 3

b)induction