Shrey's room have two electric bulbs, these bulbs are connected in series and power supplied by 220 V.

(a) Calculate the total resistance of the circuit.

(b) Calculate the current in the circuit.

(c) Calculate the voltage drop across each bulb.

Given, bulbs of 40 Ω and 70 Ω are connected in series.

Let their equivalent resistance be R_s then

R_s = 40 + 70 = 110 Ω

Hence, resistance in the circuit = 110 Ω

(b) According to Ohm's law: V = IR

Substituting the values in the formula above, we get

220 = I x 110

I = $\dfrac{220}{110}$ = 2 A

Hence, current in the circuit = 2 A

(c) Voltage drop across the 40 Ω bulb (B₁) = ?

I = 2A

Applying Ohm's Law

V = 2 x 40 = 80 V

Voltage drop across the 70 Ω bulb (B₂) = ?

I = 2A

Applying Ohm's Law

V = 2 x 70 = 140 V

Hence, voltage drop across B₁ is 80 V and across B₂ is 140 V.