Question

In a physics lab, light with a wavelength of 560 nm travels in air from a laser to a photocell in a time of 17.2 ns . When a slab of glass with a thickness of 0.880 m is placed in the light beam, with the beam incident along the normal to the parallel faces of the slab, it takes the light a time of 21.0 ns to travel from the laser to the photocell.

What is the wavelength of the light in the glass?

Use 3.00×10⁸ m/s for the speed of light in a vacuum. Express your answer using two significant figures.

Answer 1

Refractive index,

n = [((21 - 17.2) x 10^-9) x (3 x 10^8)/0.88] + 1

n = 2.295

Wavelength, lambda = 560 nm/2.295 = 2.44 x 10^2 nm

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