9.3 Electron gun

Question 1

What is an electron gun?

Answer 1

An electron gun is an electrical device that generates a stream of high-speed electrons.

Question 2

What makes up the electron gun?

Answer 2

It typically consists of a heated cathode that emits electrons, an anode to accelerate the electrons, and a focused electromagnetic field to direct the electrons in a narrow beam.

Question 3

How does the electron gun work?

Answer 3

A small metal filament is heated, known as the cathode. The electrons inside of the wire gain kinetic energy - this process is called thermionic emission. A high p.d. is applied between the filament and the anode inside a vacuum. Some electrons gain enough kinetic energy to escape the surface of the metal, and accelerate towards the anode, gaining kinetic energy. A small hole in the anode allows a line of electrons to pass through, creating a beam with specific kinetic energy.

Question 4

What is the electron gun used for?

Answer 4

Electron guns are used in a variety of applications, such as cathode ray tubes in old televisions, electron microscopes, and particle accelerators.

Question 5

What is the equation used in conjunction with the electron gun?

Answer 5

KE=(1/2)m((v)^2) V=W/Q–>W=VQ
KE=W
(1/2)m((v)^2)=VQ
Q= elementary charge e
VQ–> unit: electronvolt (eV)