How does the colour (frequency) effect the the flow of current and stopping voltage?

Once Lenard realised that the stopping voltage seemed to be the same for one colour of light no matter the intensity. He then wanted to know what a colour change would do to this new measure. He repeated the above experiment but holding the intensity as a constant but changing colours.

Do this experiment, choosing 100% intensity to hold and choosing a range of frequencies (at least 4).

Increase the potential difference in 2V increments and take current readings and observations of the electrons. Tabulate your data.

Now repeat this experiment but making the potential difference negative use 0.05 increments and then smaller increments as the photo current approaches zero. Take observations of the electrons. Type in the value rather than use the slider. Use smaller increments to get the closest stopping voltage

Combine both tables and plot the data. Repeat for other colours (at least 3 more colours)

• 1. What happens to the stopping voltage as the frequency changes? Is there a connection?

  2. Can you explain this?

Combine your stopping voltage data with other members of the class. Plot a frequency vs stopping voltage graph.

• 1. What is the relationship between frequency and stopping voltage?

  2. What is the relationship equation.

  3. Extrapolate the data so the graph shows the y-intercept.

  4. What does this value represent?