Question

The graph below shows stopping potential plotted against frequency, f.

From the graph determine:

1. Planks constant
2. Work function

Answer 1

1. Planks constant. 
   • Slope = ^h/_e = ^{(1.5 - 0)}/_{(8.5-4.5 ×10¹⁴ )} 
     ^h/_{(1.6 ×10^-19 )} = ^1.5/_{(4 ×10¹⁴ )}
     h = 6.0×10^-34Js
2. Work function 
   • w = hfo
     = 6.0×10^-34×4.0×10¹⁴
     = 2.4 ×10^-19J