Term 1 Week 5

Homework: 

Ex 10, p.189-198 Modern Physics - this will be assessed on Friday 4th March and covered the Modern Physics Topic Phy 3.5 AS 91525. This topic will be assessed in Week 8.

Electron Volts:

Some people have been getting confused by electron volts eV.
An electron volt is the amount of energy needed to move an electron through one volt of electrical potential.
Recall electrical potential energy:

E_p = qV

q: Charge in Coulombs (C)

V: Voltage in Volts (V)

The charge of one electron e = 1.60 x 10^-19 C

So the energy reqired to move one electron through one volt is:

1.60 x 10^-19 C x 1 V = 1.60 x 10^-19 J

so                       1eV = 1.60 x 10^-19 J

Using eV for energy is just a way of showing the small energies involved in one or few particle reactions. 

Always use energy in Joules when calculating. This is the S.I. unit for energy.

Converting: