JAMB - Physics (2020 - No. 8)
The effect of closing the key K in the circuit shown in the figure above would be to?
increase the current by 0.4A
reduce the current by 0.4A
increase the current by 0.6A
reduce the current by 0.6A
Explication
When K is open. Total Resistance = 8 + 2 = 10\(\Omega\)
1 = \(\frac{V}{\Omega}\) = \(\frac{6v}{\Omega}\) = 0.6A
Where K is closed, \(\frac{1}{8} + \frac{1}{8} = \frac{1}{\Omega}\)
\(\frac{2}{8} = \frac{1}{\Omega}\)
\(\Omega\) = \(\frac{8}{2}\) = 4\(\Omega\)
\(\Omega\) = \(\frac{8}{2}\) = 4\(\Omega\)
4\(\Omega\) in series with 2\(\Omega\)= 6\(\Omega\)
1 = \(\frac{V}{\Omega}\) = \(\frac{6}{6}\) = 1A
1 - 0.6A = 0.4A increase