Question

In a circuit, the cell p has an emf 1.5Vand an unknown internal resistance while the cell Q has an emf 2.0V and an internal resistance 1. If the ammeter reads 50mA what is R?

Answer 1

Internal resistance for cell p is
`9 ohm`.

Step-by-step explanation:

From the Question,

Emf of cell p & q are
`1.5v` and
`2.0v` respectively. Internal resistance of cell q is
`1ohm`.

Current reads by ammeter is
`50mA`.

So, According to question

Applying Ohm's law

`V = IR`

Where I - Current

V- Voltage

And R- Resistance

then,

`I = (V)/(R)`

`50mA = (2-1.5)/(R+1)`

`R+1 = (0.5)/(0.05)` {∵
`50 mA = 50*10^(-3) A`}

`R = 10 - 1`

`R = 9 ohm`

Therefore , Internal resistance for cell P is 9 ohm.