JEE MAIN - Physics (2017 (Offline) - No. 4)
In a coil of resistance 100 $$\Omega $$, a current is induced by changing
the magnetic flux through it as shown in the figure. The
magnitude of change in flux through the coil is:
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275 Wb
200 Wb
225 Wb
250 Wb
Explanation
According to Faraday's law of electromagnetic
induction,
$$\varepsilon = {{d\phi } \over {dt}}$$
Also, $$\varepsilon $$ = iR
$$ \therefore $$ $${{d\phi } \over {dt}}$$ = iR
$$ \Rightarrow $$ $$\int {d\phi } = R\int {idt} $$
Magnitude of change in flux (d$$\phi $$) = R × area under current vs time graph
$$ \Rightarrow $$ d$$\phi $$ = $$100 \times {1 \over 2} \times {1 \over 2} \times 10$$ = 250 Wb
$$\varepsilon = {{d\phi } \over {dt}}$$
Also, $$\varepsilon $$ = iR
$$ \therefore $$ $${{d\phi } \over {dt}}$$ = iR
$$ \Rightarrow $$ $$\int {d\phi } = R\int {idt} $$
Magnitude of change in flux (d$$\phi $$) = R × area under current vs time graph
$$ \Rightarrow $$ d$$\phi $$ = $$100 \times {1 \over 2} \times {1 \over 2} \times 10$$ = 250 Wb
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