Question

27.A battery of four cells in series each having an emf of 1.5v and internal resistance 1ohm are connected in series with an ammeter, a coil of resistance 2ohm and a filament lamp.If the ammeter reads 0.5A, the resistance of the filament lamp is

Answer 1

current in the circuit = E.M.F / total resistance .

⇒ I = E / R + r  ,  where R denotes external resistance and r denotes internal resistance in the circuit .

⇒ I = 1.5 / 10 + 5

⇒ I = 1.5 / 15

⇒ I = 0.1

therefore reading in the ammeter is 0.1 A . 

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