A bettery of emf 10 V and internal resistacne `3 Omega` is connected to a resistor. If the current in the circuit is `0.5A,` what is the resistance of the resistor ? What is the terminal voltage of the bettery when the circuit is closed ?

Explanation

For the adjoining closed loop,
`I = (epsilon)/(R + r)`
`therefore R +r = (epsilon)/(I)`
`therefore R = (epsilon)/(I) -r `
= `(10)/(0.5) - 3 `
`therefore R = 17 Omega`
Terminal voltage of battery,
`V_(ab) = IR `
= (0.5) (17)
= 8.5 V
OR
V = `epsilon - `Ir
`= 10 - (0.5) (3)`
= 10 - 1.5
= 8.5 Volt