If two electric bulbs have 40 W and 60 W ratings at 220 V, then the ratio of their resistances will be
Options
(a) (3:2)
(b) (2:3)
(c) (3:4)
(d) (4:3)
Correct Answer:
(3:2)
Explanation:
P = V² / R
⇒ R₁ / R₂ = P₂ / P₁ = 60 / 40 = 3 / 2 = 3 : 2
If two electric bulbs have 40 W and 60 W ratings at 220 V, then the ratio of their resistances will be
(a) (3:2)
(b) (2:3)
(c) (3:4)
(d) (4:3)
(3:2)
P = V² / R
⇒ R₁ / R₂ = P₂ / P₁ = 60 / 40 = 3 / 2 = 3 : 2