光电二极管

• ⺌(small light radiating upward)ASSOCIATIVE
• 兀(standing person; upright person)ASSOCIATIVE

Light shining down from above a person standing upright creates the image of 光, meaning light.

• 曰(speak; bright cloud)ASSOCIATIVE
• 乚(lightning bolt; hook stroke (downward))ASSOCIATIVE

A flash of lightning bursts bright through the clouds—that is electricity itself!

• 二(number two; two horizontal strokes)ASSOCIATIVE

Two parallel horizontal strokes symbolize the number two.

• 木(tree; wood)RADICAL
• 及(reach; attain; catch up)PHONO-SEMANTIC

An extreme point is the uttermost end of a wooden pole, where a hand just barely reaches.

• ⺮(bamboo)RADICAL
• 官(official; manage)PHONO-SEMANTIC

A bamboo tube is managed by officials, so 管 means both tube and to manage.