Question

While riding bike on highway, we observe that traffic signal turns red from green. Explain the principle that is used in maintaining traffic signals . Class 12 physics

Answer 1

Traffic signals are lights which follow a universal colour code, to control flow of traffic and signal the right of way to road users. Traffic lights are made of LED (Light Emitting Diode) and the colours have been chosen, to provide maximum visibility.

Green light allows traffic to proceed in direction shown, amber light warns of imminent change of light to red or green and red signals traffic to stop completely from proceeding. There might be minor variations from country to country, but the general idea remains the same universally.