question_answer

An ammeter reads upto 1 A. Its internal resistance is \[0.81\,\,\Omega \]. To increase the range to 10 A, the value of the required shunt is     AIEEE  Solved  Paper-2003

A) \[0.03\,\,\Omega \]

B)                       \[0.3\,\,\Omega \]                         

C)       \[0.9\,\,\Omega \]                         

D) \[0.09\,\,\Omega \]

Correct Answer: D

Solution :

To increase the range of ammeter we have to connect a small resistance in parallel (shunt), let its value be R.             Apply KCL at junction to divide the current: Voltage across R = Voltage across ammeter             \[\Rightarrow 9R=0.81\times 1\]              \[\Rightarrow R=\frac{0.81}{9}=0.09\,\,\Omega \]