a ray of light strikes a flat, 2-cm thick block of glass(n=1.5) at an angle of 30 degrees with respect to the normal. find the angle of refraction at the top surface. find the angle of incidence at the bottom surface and the refracted angle. find the lateral distance by which the light beam is shifted. calculate the speed of the light in the glass and the time required for the light to pass through the glass block. is the travel time through the block affected by the angle of incidence? explain.

1 answer

sin 30/sin T2 = 1.5/1
sin T2 = .5/1.5 = .333...
T2 = 19.5 degrees

distance through glass at 0 degrees from normal is given = .02 meter

distance throgh glass if NO refraction
= .02 /cos 30 = .0231 meter

actual distance through glass at 19.5 deg
= .02 / cos 19.5 = .0212 meter

if it hits bottom surface at 19.5 deg, it will exit into the air at 30 degrees

It will however be moved sideways
distance moved =d
sin(30-19.5) = d / .0212
d = .0212 sin 10.5 = .00386 meters = .386 cm

speed in glass = c/1.5 = 3*10^8/1.5 = 2*10^8m/s

time in glass = .0212 /2*10^8 = 1.06 *10^-10 seconds

yes, of course, path length in glass depends on angle so time does as well.