A) A negatively charged electroscope can be discharged by shining an ultraviolet

Question

A) A negatively charged electroscope can be discharged by shining an ultraviolet light on it. How does this happen?

B) You might think that an ultraviolet light shining on an initially uncharged elctroscope would cause the electroscope to become positively charged as photoelectrons are emitted. In fact, ultraviolet light has no noticable effect on an uncharged electroscope. Why not?

1. a. A negatively charged electroscope can be discharged by shining an ultraviolet light on it. How does this happen? UV light b. You might think that an ultraviolet light shining on an initially uncharged electroscope would cause the electroscope to become positively charged as photoelectrons are emitted. In fact, ultraviolet light has no noticeable effect on an uncharged electroscope. Why not?

Explanation / Answer

Theory: A photoectron is an electron emitted from an atom by interaction with a photon, especially an electron emitted from a solid surface by the action of light of suitable energy.

Now, when the elecroscope is negatively charged , it is because it has some extra electrons which are loosely attached to the atoms of the electroscopic material. These electrons can be knocked out of these atoms by shining ultravilet light on the electroscope as the photons wills hit the electons and provide them enoungh kinetic energy to get out of the atoms.

But when the electoscope is neutral , no such loosely bonded electrons are present . THEREFORE, the neutral electroscope will not get positive charged since the electrons will not be provided the required KE ( which high enough now) to get out of the atoms.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.