The three circuits below contain idenocal bulbs and identica

The three circuits below contain idenocal bulbs and identical battery Assume the batteries ideal (i.c., the batteries have no resistance). a. Rank the current of the five bulbs. b.Explain how you determined your answer.

Solution

suppose resistance of bulb is R. then

current through A will be

Ia = e / R

in circuit 2:

Req = R + R = 2R

current through B and C will be same (as they are connected in series)

Ib = Ic = e / 2R

In circuit 3:

D and E are connected in parallel with battery .

hence PD across D and E will be e.

so current through D and E , Id = Ie = e / R

Ib = Ic < Ia = Id = Ie