Please Help! Physics-EM Waves

Question

Combing your hair leads to excess electrons on the comb. How fast would you have to move the comb up and down to produce green light? (Assume λ = 569 nm.)

Answer 1

c = λν

ν = c/λ

ν= 3x10^8 ms^-1/569x10^-9 m

ν = 5.27x10^14 times/sec