Graph (1 Viewer)

[clever angel]

hi ppl,

Wavelength(*10-7m) Kinetic energy(10-19 j) Frequency sued ( )
5.5 8.01
4.3 1.60
4.1 1.92
3.6 2.56
3.1 3.36
Complete the table icluding correct units for frequencyand then using the eqauiton
Photoelectric equation plot K.E vs frequency and calculate planks concstant and work function

sorry spelling mistakes, plzzz do it
i seriously need help

 

[Jago]

I don't get what you're asking.

 

[KFunk]

Working out frequency first... We're dealing with EMR so:

c = f x (wavelength) ----> frequency = c/wavelength

If you plot KE versus frequency then what you're graphing is:

KE = hf - W_o i.e Kinetic energy as a function of frequency. Where:
- KE is the kinetic energy of a photoelectron impacted by a photon of frequency f
- hf is the energy of the impacting photon
- W_o is the energy required to remove an electron from the given material

Graphing your points you should come up with a linear function with an x-intercept and a y-intercept. Now you need to note the following:

KE = hf - W_o is in the form y = mx + b , hence m=h which means you can calculate the value of planck's constant by working out the gradient of your line. This can be done with the formula m = (y₂ - y₁)/(x₂ - x₁) using the values form your table where x coordinates are you frequency values and KE is your y.

if you let x (i.e f) = 0 to find the y-intercept then this will give you the value of the work function W_o. You can just do this by looking at the graph and estimating a rough value for W_o by looking at where the line touches the y-axis. I hope this helps.