-A student creates a two-point source interference pattern in a ripple tank with two sources operating in phase and records the following information: n =4, l = 37.5 mm, L = 1.25 m, d= 24 cm. Calculate x4.

-A Quartz (n = 1.46) is often used as a countertop replacement and it mimics the properties of granite. Determine the critical angle of quartz.

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