Question

When a ray of light enters a glass slab from air its wavelength decreases its wavelength increases its frequency increases neither its wavelength nor its frequency change

Answer 1

As the light enters from rarer medium to the denser medium, the speed of light decreases but the frequency remains the same.
The relation between Speed of light, wavelength and frequency is given as:
V=nλ
where V is speed
n=frequency of light
λ= wave length
n=v/λ
in denser medium, speed decreases , therefore wavelength also decreases. to keep frequency constant.
∴Option 1 is correct wavelength decreases