Question

Why is there gold on the inside of a cell phone but plastic on the outside

Answer 1

Answer:

Gold is chemically stable and conducts electricity.

Small pockets of gold are used to make mobile phone circuit board.

The plastic is lined to act as antenna gate. It's what makes a phone not a calculator but a communication point, since it allows the data flow, Bluetooth connection, Wi-Fi. Mainly, it allows radio waves to flow.

Answer 2

There is gold on the inside of a cell phone because it blocks the distributed  signals and plastic is just there to make sure nothing scratch it.