MHT CET · Physics · Electromagnetic Induction
Magnetic flux passing through a coil is initially \(4 \times 10^{-4} Wb\). It reduces to \(10 \%\) of its original value in \(t\) second. If the emf induced is 0.72 mV then \(t\) in second is
- A 0.3
- B 0.4
- C 0.5
- D 0.6
Answer & Solution
Correct Answer
(C) 0.5
Step-by-step Solution
Detailed explanation
\(\phi_1=4 \times 10^{-4} \quad Wb\)
\(\phi_2=0.1 \times \phi_1=4 \times 10^{-5} Wb\)
\(\varepsilon=0.72 mV\)
\(\therefore t=\) ?
Using \(\varepsilon=-\frac{d \phi}{d t} \Rightarrow d t \Rightarrow \frac{d \phi}{\varepsilon}\)
\(=\frac{4 \times 10^{-4}-4 \times 10^{-5}}{72 \times 10^{-5}}=\frac{4 \times 10^{-5}(9)}{72 \times 10^{-5}}=\frac{1}{2}=0.5 s\)
\(\phi_2=0.1 \times \phi_1=4 \times 10^{-5} Wb\)
\(\varepsilon=0.72 mV\)
\(\therefore t=\) ?
Using \(\varepsilon=-\frac{d \phi}{d t} \Rightarrow d t \Rightarrow \frac{d \phi}{\varepsilon}\)
\(=\frac{4 \times 10^{-4}-4 \times 10^{-5}}{72 \times 10^{-5}}=\frac{4 \times 10^{-5}(9)}{72 \times 10^{-5}}=\frac{1}{2}=0.5 s\)
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