00:01
For this question, we have potassium.
00:03
The work function is 3 .68 times 10 to the minus 19 joules.
00:11
And wavelength, 300 nanometers.
00:17
And sodium, work function, 4 .41.
00:30
There's 10 to the minus 19 joules.
00:32
Also wavelength 300 nanometers, which emits electrons with the greater velocity, and what's the velocity of these electrons.
00:42
So the energy here will first start to solve.
00:50
Well, the energy for both of these is equal to hc over lambda.
00:55
So h is planck's constant.
01:01
Speed of light, 3 times 10 to 8 meters per second.
01:05
Wave length is 309 meters.
01:10
This gives us an energy of 5 .09 times 10 to the minus 19 joules.
01:18
And then to calculate the by the 5.
01:22
Velocity, energy is equal to the work function plus a half mb squared.
01:30
So we'll do this for both potassium and sodium squared.
01:51
So energy.
02:05
The work function of sodium, work function of potassium...