Sketch a sinusoidal wave with an amplitude of $2 \mathrm{cm}$ and a wavelength of $6 \mathrm{cm} .$ This wave represents the electric field portion of a visible EM wave traveling to the right with intensity $I_{0}$. (a) Sketch an identical wave beneath the first. What is the amplitude (in centimeters) of the sum of these waves? (b) What is the intensity of the new wave? (c) Sketch two more coherent waves beneath the others, one of amplitude $3 \mathrm{cm}$ and one of amplitude $1 \mathrm{cm},$ so all four are in phase. What is the amplitude of the four waves added together? (d) What intensity results from adding the four waves?