Physics Homework: Determine the voltage across the resistor..

Q) A battery has three cells connected in series, each with an internal resistance of 0.024Ω and an emf of 1.80V . This battery is connected to a 15.0Ω resistor.

Determine the voltage across the resistor.

Sol:

Since three cells are connected in series, Hence total internal resistance will be equal to, r= 3*0.024=0.072Ω

The current flowing through the circuit is given by,

I= (EMF/R) + r, where EMF=1.80V, R=15.0Ω, r= 0.072Ω

Therefore I= (1.80/15) + 0.072

           = 0.192A

The voltage across the resistor R=15.0Ω is given by,

V_R = IR

   = 0.192*15

   =2.880V