The wavelength of blue light changes from $4.7 \\times 10^{-7}\\,\\text{m}$ to $3.5 \\times 10^{-7}\\,\\text{m}$ when it moves from air into water. What is the speed of this light in water?
- A$7.4 \times 10^{7}\,\text{m s}^{-1}$
- B$1.3 \times 10^{8}\,\text{m s}^{-1}$
- C$2.2 \times 10^{8}\,\text{m s}^{-1}$
- D$3.0 \times 10^{8}\,\text{m s}^{-1}$