Question

An electrical meter of internal resistance 20$\Omega$ gives a full scale deflection when one milliampere current flows through it. The maximum current, that can be measured by using three resistors of resistance 12$\Omega$ each, in milliamperes is

• A. 10
• B. 8
• C. 6
• D. 4

Answer 1

Answer: (C)

6

$\frac{L^i}{i_2}=\frac{R^2}{R_1}$

for maxm current resistance should be parallel

= $=R_2=\frac{12}{3}=4\Omega$

$\therefore \frac{1}{i_2}=\frac{4}{20}$

$i_2=5A$

$\therefore$i , Total current $=i_1+i_2=6A$