# Bulb B1(40W, 220V) connected to a 220V supply glows with some brightness. Predict the change in brightness(if any) with reason if another identical bulb B2(40W, 220V) is connected in:- (a) Series to B1 (b) Parallel to B1

1
by vipinDeo234

2015-08-21T00:37:23+05:30

### This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
B1 : Rated values :  P1 = 40W  and V1 = 220 V
R1 = V1² / P1 = 220 * 220 / 40 = 1210  Ω
I1 = P1/V1 = 2/11 A  = rated current

Bright is dependent on the power dissipated by the bulb. ie., on I^2 R or  V^2/R.

B2 : also has same rated values.  P2 = 40 W,  V2= 220 V,
R2 = 1210 Ω  and  I2 = 2/11 A.
===========
a)  Now, two bulbs are in series.  Both are equivalent.
Voltage = V1' = 220/2 = 110 V        Current I1'= 110 / 1210 = 1/11 A
So power dissipated through a bulb = V1' * I1' = 10 W
As Voltage becomes 1/2 V1, power becomes 1/4 th  P1.  So the bulb glows with much reduced brightness.
===================
b) If the bulbs are connected in parallel, as the case is usually in real life, each bulb draws :  220 Volts and current of 2/11 Amp  which are rated values.
Hence the bulbs will glow at their rated brightnesses.

click on thanks button above please