How will be the reading in the ammeter A affected if another identical bulb Q is connected in parallel to P? (The voltage in the mains is maintained at a constant value.)

Let, resistance of bulb P and Q be R. So reading of ammeter before connecting Q to the circuit is I=VR                                                           ?.(i) After connecting Q to the circuit, resultant resistance of the circuit is 1Req=1R+1R=2Ror Req=R2Ω Thus, new reading of ammeter will be l′=VR/2=2VR or         l′=2l                          (From (i))