JAMB - Physics (2006 - No. 18)
An ammeter of resistance 5Ω has a full-scale deflection when a current of 50 mA flows in it. The value of the resistor required to adapt it to measure a current of 5 A is?
0.25Ω
5.00Ω
19.80Ω
0.05Ω
Giải thích
R\(_s\) = \(\frac{(i_gr_g)}{I-i_g}\) = \(\frac{(50 \times 10^{-3} \times 5)}{5 - (50 x 10^{-3})}\) = \(\frac{(0.25)}{4.95}\) = 0.0505 = 0.05Ω