Question

a television remote control operates at 319 THz, what is the wavelength of the infrared light in nanometers?

Answer 1

Given:

Frequency (ν) = 319 THz

To determine:

The wavelength corresponding to the given frequency

Explanation:

Wavelength (λ) and Frequency(ν) are related as:

λ = c/ν

where c = speed of light = 3*10⁸ m/s

Now:

SI unit of frequency is Hertz (Hz) also expressed as cycles per second

i.e 1 Hz = 1 s⁻¹

1 Terahertz (THz) = 10¹² Hz

therefore the given frequency ν = 319 *10¹² s⁻¹

λ = 3 * 10⁸ ms⁻¹/319 *10¹² s⁻¹ = 940 * 10⁻⁹ m

since 1 nanometer (nm) = 10⁻⁹ m

The wavelength is λ = 940 nm

Ans: The infrared wavelength = 940 nm