An infared wave has a wavelength of 1.5 x10^–6 m. The speed of this wave is 2.2 × 10^8 m/s. Calculate the frequency of the wave. Give your answer in standard form and to 2 significant figures.

First, I would highlight the numbers you need to use for this question and label them as v and λ. This makes them easier to find once you start inputting them into the calculator. Find the equation you need on your equation sheet, this will include speed (v), frequency (f) and wavelength(λ) - λ = v/f. Rearrange formula for f and write this down in your working - f = v/ λ. Substitute the numbers in the question into this equation to find frequency Answer is 1.5 x 10^14 Hz (make sure to write to 2 sig fig otherwise you'll lose a mark).