JIPMER2009PhysicsCurrent Electricity
The resistance of an ammeter is 13 and its scale is graduated for a current upto 100 A . After an additional shunt has been connected to this ammeter it becomes possible to measure currents upto 750 A by this meter. The value of shunt resistance is
Options
- A20
- B2
- C0.2
- D2 k
Correct answer
B. 2
Step-by-step solution
Let i_a is the current flowing through ammeter and i is the total current. So, a current i-i_a will flow through shunt resistance. Potential difference across ammeter and shunt resistance is same. ie, i_a R= (i-i_a ) S or S= i_a R i-i_a (i) Given, i_a=100 ~A , i=750 ~A , R=13 Hence, S= 100 13 750-100 =2