Electroscopes

Effect of UV Light

 UV light causes the ejection of electrons from the metal surface if the photon energy is greater than the work function of the metal. This is the photoelectric effect in action.

Positive Electroscope Behavior:

For a positively charged electroscope, the ejection of electrons increases the positive charge, causing the leaves to spread further apart.

Negative Electroscope Behavior:

For a negatively charged electroscope, the ejection of electrons decreases the negative charge, causing the leaves to move closer together.

Threshold Frequency

 If the light used has a frequency below the threshold frequency (such as visible light), no electrons will be ejected, and the leaves' position will not change.