'Its wavelength is about 500 to 550 nanometers, & it means "go"'
green
SEEING THE LIGHT: Its wavelength is about 500 to 550 nanometers, & it means go
Its wavelength is about 500 to 550 nanometers, & it means "go"
Its wavelength is about 500 to 550 nanometers, & it means "go"
SEEING THE LIGHT
green
SEEING THE LIGHT