JEE Main & Advanced
JEE Main Online Paper (Held on 9 April 2013)
question_answer
A shunt of resistance 1\[\Omega \] connected across a galvanometer of 120\[\Omega \]resistance. A current of 5.5 ampere gives full scale deflection in the galvanometer. The current that will give full scale deflection in the absence of the shunt is nearly:
JEE Main Online Paper (Held On 09 April 2013)
A) 5.5 ampere
B) 0.5 ampere
C) 0.004 ampere
D) 0.045 ampere
Correct Answer:
D
Solution :
\[{{r}_{A}}=\frac{l\times 120}{120+1}=\frac{120}{121}=1\,\,\Omega \] \[V=l(R+1)\] \[V=5.5(R+1)\] Without short resistance \[V=l'(R+120)\] ...(ii) Eq. (i) is equal to Eq. ?(ii) \[5.5(R+1)=l'(R+120)\] Hence, if the circuit has no resistance \[R=0\] \[5.5=l'(120)\]\[l'=\frac{5.5}{120}=0.045\,A\]