A) The value of R for normal brightness of each lamp is (3/4) W
B) The value of R for normal brightness of each lamp is (21/4) W
C) Total power dissipated in circuit when all lamps are normally bright is 24W
D) Power dissipated in R is 21W when all lamps are normally bright
Correct Answer: B
Solution :
For normal brightness of each bulb see following circuit. Current through each bulb = 0.5 A So main current \[i=2A\] Also, voltage across the combination \[=1.5\,V\] So voltage across the resistance \[=10.5\,V\] Hence for resistance \[V=i\,R\] Þ\[10.5=2\times R\] Þ\[R=\frac{21}{4}\Omega \]You need to login to perform this action.
You will be redirected in
3 sec