Question

Figure below shows two resistors R₁ and R₂ connected to a battery having an emf of 40V and negligible internal resistance. A voltmeter having a resistance of. 300 Ω is used to measure the potential difference across R₁ Find the reading of the voltmeter.

Answer 1

R₁ and R₃ are in parallel.
∴     Current I in the circuit remains unchanged in R₁ and R₃ combination and R₂ 
                              `1/(R') = 1/200 +1/300 =5/600`

                             `R' = 600/5 = 120  Omega `

∴     R_{Equivalent in circuit} = 120 + 880 = 1000 Ω

I, current.in the circuit =`40/1000 A`

                              ∴ V =` 40/1000 xx 120`

⇒                               `V = 48/10`
∴                                V = 4.8 V