When a beam of light with wave length $\lambda= 6000 A,$ travelling in air, enters a glass medium whose refractive index is 1.5 then,

Question

(a)frequency of light remains constant

(b)velocity of light increase by 1.5 times

(c)frequency of light increase by 1.5 times

(d)wavelength $(\lambda)$ of light decreases by 1.5 times