Question

when a resistance of 20 ohm is connected in series with a battery a current of 0.5 A flow through it when resistor of 10 ohm connected the current is 0.8 A. internel resistance of battery is

Answer 1

Answer is : 6.67 ohm

E1=I1(R1+r)

E1=0.5(20+r)----(1)

E2=I2(R2+r)

E2=0.8(10+r)----(2)

As E1=E2

0.5(20+r)=0.8(10+r)

r=6.67

And thats the answer.