## Kinetic energy

Kelly Zhang 1L
Posts: 31
Joined: Fri Sep 28, 2018 12:18 am

### Kinetic energy

Are there any physical signs/properties that indicate how fast the kinetic energy of an ejected electron is?

Posts: 62
Joined: Fri Sep 28, 2018 12:23 am

### Re: Kinetic energy

I'm also wondering the same thing. I know we can calculate the kinetic energy through using a detector although are there any other physical signs we can look for?

Michael_Navarro_1H
Posts: 29
Joined: Fri Sep 28, 2018 12:17 am

### Re: Kinetic energy

For our purposes I think the only way to determine the velocity of an electron other than a detector is by utilizing the equation provided to us in class: E(photon) - E(energy remove e-) = 1/2mv^2

Matthew Tran 1H
Posts: 165
Joined: Fri Sep 28, 2018 12:16 am

### Re: Kinetic energy

It would be extremely hard to notice any 'physical' signs because an electron is incredibly small, much, much smaller than an atom! So like Michael said, it's most likely that the detector can only detect the velocity of the ejected electrons. We know the mass of an electron experimentally = 9.11x10-31kg, so if we know an electron's velocity, we can calculate its kinetic energy. Obviously the converse is true as well: if we know the electron's kinetic energy, we can calculate its velocity.

Kelsey Warren 1I
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

### Re: Kinetic energy

You can't really measure "how fast" the kinetic energy of anything is. Kinetic energy is directly proportional to the velocity of the particle squared, so I guess you could say a physical sign of the kinetic energy of an ejected electron is the square root of its velocity.