An ammeter has a current range of 0 – 5 A, and its internal

An ammeter has a current range of 0 – 5 A, and its internal resistance is 0.2 Ω. In order to change the range to 0 – 25 A, we need to add a resistance of

1. 0.8 Ω in series with the meter
2. 1.0 Ω in series with the meter
3. 0.04 Ω in parallel with the meter
4. 0.05 Ω in parallel with the meter

For 25A,
Let 5A through ammeter A₁.
So, remaining current through R_sh,
I = 25 – 5
= 20 A
∴ 20 × R_sh = 0.2 × 5
⇒ R_sh = 1/20 = 0.05Ω