Two light bulbs shown in the circuit have rating `A(24 V, 24W) and B(24 V and 36W)` as shown. When the switch is closed,

Options

A. the intensity of light bulb A increases.
B. the intensity of light bulb A decreases
C. the intensity of light bulb B increases
D. the intensity of light bulb B decreases

Answer

B, C

Explanation

b., c.
For a bulb `R = V^2/W` or `R_(B)leR_(A)`
when switch is open `I_A = I_(B)`
`P_(A) = R_(A)I_(A)^(2)`
`P_A = R_(A)I_(A)^(2)`
`P_(B)ltP_(A)` and `V_(A)gtV_(B)`
`V_(A)gt12V` and `V_(B) lt 12V`
After closing the switch
`V = V_(B) = 12 V` or `P_(B) = 36W`
`P_(A) = 24W` .