Assume that the wave length of yellow light in crown glass of refractive index 1.5 is 600 nm. Its frequency is a) 0.5 x1015 Hz b) 0.33 x1015 Hz c) 1.5 x1015 Hz d) 0.5 x1015 Hz

To find the frequency of yellow light in crown glass, we use the fundamental wave equation:

Velocity of light in a medium:
v = c / n

where
c = speed of light in vacuum = 3 × 10^8 m/s
n = refractive index of the medium = 1.5

So,
v = (3 × 10^8) / 1.5
v = 2 × 10^8 m/s

Now, we use the wave equation:
v = fλ

where
f = frequency (to be found)
λ = wavelength in the medium = 600 nm = 600 × 10^-9 m

Rearranging for frequency:
f = v / λ
f = (2 × 10^8) / (600 × 10^-9)

Solving,
f = (2 × 10^8) × (10^9 / 600)
f = (2 × 10^17) / 600
f = (2 / 6) × 10^15
f = 0.33 × 10^15 Hz

Thus, the correct answer is:
b) 0.33 × 10^15 Hz