What is the purpose of an optocoupler?

• A. Isolates electronic devices using light and diodes
• B. Converts electrical signals to wireless signals
• C. Amplifies current in a power supply
• D. Stores digital data

Answer: (A)

The main idea being tested is electrical isolation between two circuits while still allowing signal transfer through light. An optocoupler uses an LED on the input side and a light-sensitive detector (like a phototransistor or photodiode) on the output side, with a barrier between them. When the input is driven, the LED emits light that travels across the barrier and is detected, producing an electrical signal on the output. The barrier prevents current or voltage from passing directly, so high voltages, noise, or transients on one side don’t affect the other. This makes optocouplers ideal for safely interfacing low-voltage control circuitry with high-voltage or noisy environments.

They don’t convert signals to wireless, they don’t amplify power, and they don’t store data, which is why the other uses don’t fit.