JAMB - Physics (1995 - No. 31)
If a resistance is halved in value and the potential difference across it is tripled, then the ratio of the new current to the old one is
1 : 6
1 : 3
2 : 1
6 : 1
Giải thích
\(\frac{V_1}{V_2}\) = \(\frac{I_1R_1}{I_2R_2}\)
\(\frac{I_1}{I_2}\)V2 = 3V1 and R1 = 2R2
\(\frac{V_1}{3V_1}\) = \(\frac{I_1 \times\ 2R_2}{I_2\times R_2}\)
\(\frac{I_1}{I_2}\) = \(\frac{6}{1}\)
\(\frac{I_1}{I_2}\)V2 = 3V1 and R1 = 2R2
\(\frac{V_1}{3V_1}\) = \(\frac{I_1 \times\ 2R_2}{I_2\times R_2}\)
\(\frac{I_1}{I_2}\) = \(\frac{6}{1}\)