Question

1 Calculate the wavelength (in nm) of a the red light emitted by a neon sign with a frequency of 4.74x104 Hz A) 633 nm B) 158 nm C) 142 nm D) 704 nm E) 466 nm

Answer 1

frequency = 4.74 x 10^14 Hz

C = light velocity = 3 x 10^8 m /sec

wave length =   C / frequency

                    = (3 x 10^8 ) / (4.74 x 10^14)

                    = 6.33 x 10^-7 m

                    = 633 x 10^-9 m

                    = 633 nm

answer : A ) 633 nm