The conversion of voltage to current when exposed to light
The conversion of light to electrical energy✓Correct answer
The effect that causes a photodiode to emit light when a voltage is applied
The effect that causes a phototransistor’s beta to decrease when exposed to light
Explanation
The photovoltaic effect is the direct conversion of light into electrical energy: absorbed photons create electron-hole pairs that the junction's built-in field separates, producing a voltage at the terminals. Emitting light in response to an applied voltage is the opposite process, and the remaining choices misstate what the effect converts.