A narrow beam of light passes through a clear acrylic block and then out into the air. Inside the acrylic, the light has a wavelength of 420 nm420\ \mathrm{nm}420 nm and travels at 2.0 × 108 m/s. In the air, it travels at 3.0 × 108 m/s. The source fixes the frequency of the light.
What is the wavelength of the light after it leaves the block?
630 nm630\ \mathrm{nm}630 nm
560 nm560\ \mathrm{nm}560 nm
420 nm420\ \mathrm{nm}420 nm
280 nm280\ \mathrm{nm}280 nm
84 exam-style questions on Edexcel GCSE Physics 5.2 The electromagnetic spectrum, covering 5.2.1 Electromagnetic waves and refraction in glass (core practical), 5.2.2 Groups of the electromagnetic spectrum, 5.2.3 Wavelength-dependent behaviour of EM waves, and 5.2.4 Velocities of EM waves in different substances. Each one has a worked solution and a mark scheme showing where the marks go.