Electromagnetic Induction and Alternating Current 3 Question 2
2. Two coils $P$ and $Q$ are separated by some distance. When a current of 3 A flows through coil $P$, a magnetic flux of $10^{-3} Wb$ passes through $Q$. No current is passed through $Q$. When no current passes through $P$ and a current of 2 A passes through $Q$, the flux through $P$ is
(a) $6.67 \times 10^{-3} Wb$
(b) $6.67 \times 10^{-4} Wb$
(c) $3.67 \times 10^{-3} Wb$
(d) $3.67 \times 10^{-4} Wb$
(Main 2019, 9 April II)
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Answer:
Correct Answer: 2. (b)
Solution:
- As, coefficient of mutual induction is same for both coils
Here,
$$ \begin{aligned} N _P & =N _Q=1, \\ \varphi _{P Q} & =?, \varphi _{Q P}=10^{-3} Wb \\ I _Q & =2 A, I _P=3 A \end{aligned} $$
Substituting values in $Eq$ (i), we get
$$ \begin{aligned} \varphi _{P Q} & =\frac{I _Q \cdot \varphi _{Q P}}{I _P}=\frac{2}{3} \times 10^{-3} \\ & =0.667 \times 10^{-3}=6.67 \times 10^{-4} Wb \end{aligned} $$
