Question

It is intended to measure a maximum current of 25 A with an ammeter of range 2.5 A and resistance 0.9Ω. How will you do it? What will be the combined resistance?

Answer 1

Answer:

The answer is 0.2 ohms

Explanation:

G = 10 ohms

Ig = 50 mA = 0.05A

I = 2.5 A

S= Ig*G / I - Ig

S = 0.05*10/2.5-0.05

= 0.5 / 1.45

S= 0.204 ohms ( in parallel)

Therefore, the resistance of the ammeter so required is...

Ra = GS/ G+S

= 10 ( 0.204)/ 10+ 0.204

Ra= 0.199 ohms

Ra = 0.2 ohms

HOPE IT HELPS