Explain the incomplete dominance with example.

Incomplete dominance neither the allele of a gene is dominant nor recessive. So that heterozygote show intermediate trait between the two parental traits.
In four '0' clock plants red colour flower producing plant is crossed with whight flower producing plant.
In F₁ generation all progeny form pink coloured flowers intermediate. 
$\underset{\text{ Red }}{\mathrm{RR}}\times \underset{\text{ White }}{\mathrm{rr}}$
F₁ progeny $\to$ Rr pink colour flowered progeny
Self pollination of F₁ progeny result in Red, pink, white, flowers in 1:2:1 ratio
Phenotypic ratio = genotypic ratio