Question

A photocell contains a barium metal surface. How does the presence of barium contribute to the photocell's function, and what role does it play in the generation of electric current?

Answer 1

Barium metal in a photocell is essential for the photoelectric effect, where incoming photons eject electrons from the surface, creating an electric current that can activate mechanisms like automatic doors.

Step-by-step explanation:

The presence of barium in a photocell contributes significantly to its function based on the photoelectric effect. Barium has a low work function, making it easier for incoming photons of light to eject electrons from its surface when exposed to light above a certain threshold frequency. This ejection of electrons is essential for the generation of electric current in the photocell. When light hits the barium surface, electrons are emitted and move toward the anode, creating a current. If light is interrupted, as by someone passing through an automatic door, the current drops, which can be used to trigger a response such as opening the door.