Additional Information

Each photocell contains a metal. A photon of light that strikes the metal can eject an electron from the metal if the photon’s energy exceeds the metal’s work function. The maximum kinetic energy the ejected electron can have is the photon’s energy minus the metal’s work function. The amount of electrical current varies with light’s relative intensity (a measure of the number of photons with a given energy striking the metal each second).

 

Table 1 shows the results of 9 trials in which a photocell was exposed to light.

 

Table 1

Table
Trial	Energy per photon (eV)*	Relative intensity of light	Electrical current (mA)†	kinetic energy of electron if ejected from metal (eV)
1	2.0	low	0	0.0
2	2.0	medium	0	0.0
3	2.0	high	0	0.0
4	4.0	low	29	0.9
5	4.0	medium	43	0.9
6	4.0	high	60	0.9
7	6.0	low	27	2.9
8	6.0	medium	40	2.9
9	6.0	high	55	2.9
*eV = electron volts
†mA = milliamps

When 8.0 eV photons were shone on the photocell, electrons ejected from the metal in the photocell had a maximum kinetic energy of 4.9 eV.

Based on this information and Table 1, the relative intensity of the light shone on the photocell: