3.12 - DEFINITIONS

Question 1

Anode?

Answer 1

a positively charged electrode

Question 2

Cathode rays?

Answer 2

beams od electrons emitted from a cathode through thermionic emission

Question 3

Cathode?

Answer 3

a negatively charged electrode

Question 4

Discharge tube?

Answer 4

A sealed glass tube held at low pressure, with an anode at one end and a cathode at the other. When the elctrodes are connected to a supply, the gas in the tube will glow and coonduct electricity.

Question 5

Electron gun?

Answer 5

A pair of electrodes that produce a thin and fast moving beam of electrons

Question 6

Negative glow?

Answer 6

A glow found near the cathode in a discharge tube; caused by the recmbination of positive ions with the electrons produced by ionisation, resulting in photons being emitted

Question 7

Paddle wheel?

Answer 7

a whee found in a dischage tube that demonstrates the presence of cathode rays

Question 8

Specific chage?

Answer 8

the ratio of mass to charge

Question 9

Stpping potential?

Answer 9

a value of potetial difference a which photoelectric emission is stopped; this is because the electrons no longer have sufficient kinetic energy to cross the potential difference