Question

A glass plate $(n=1.53)$ that is $485\mu m$ thick and surrounded by air is illuminated by a beam of white light normal to the plate, (a) What wavelengths in the visible spectrum $(400$ or $700nm)$ are intensified in the reflected beam? (b) What wavelengths are intensified in transmitted beam?

Answer 1

In reflected light $2\mu t=(2n+1)\frac{\lambda }{2}$
$\lambda =\frac{4\mu t}{2n+1}=\frac{2970}{2n+1}nm=594nm,424nm$
In transmitted light $2\mu t=n\lambda$ or $\lambda =\frac{2\mu t}{n}=\frac{1485}{n}$
$=495nm$.