2PE: Concepts of Wavelength and Frequency Two electromagnetic waves are represented in the margin, (a) Which wave has the higher frequency? (b) If one wave represents visible light and the other represents infrared radiation, which wave is which? If one of the waves in the margin represents blue light and the other red light, which wave is which?
Solution: Here, we are asked to identify the red and blue light from the given waves. Step1: White light consists of light of seven different colours, with different frequencies. When these coloured lights pass through the prism, each of them deviates by different angles and we see the ‘VIBGYOR’ colours as shown below: Thus, red light has longer wavelength than blue light. Step2: Wavelength is the distance between two consecutive crests of a wave. Thus, longer the wave, longer will be the wavelength. Step3: Now, out of the two waves given in the problem, wave 1 has longer wavelength than wave 2. Thus, wave 1 is red light whereas wave 2 is blue light. ------------------------