a
\(\phi=\overrightarrow{ B } \cdot \overrightarrow{ S }\)

\(\phi=\frac{4}{\pi} \times 10^{-3}\left(1-\frac{ t }{100}\right) \cdot \pi R ^{2}\)

\(\phi=4 \times 10^{-3} \times(1)^{2}\left(1-\frac{t}{100}\right)\)

\(\varepsilon=\frac{- d \phi}{ dt }\)

\(\varepsilon=\frac{- d }{ dt }\left(4 \times 10^{-3}\left(1-\frac{ t }{100}\right)\right)\)

\(\varepsilon=4 \times 10^{-3}\left(\frac{1}{100}\right)=4 \times 10^{-5} V\)

When \(B=0\)

\(1-\frac{t}{100}=0\)

\(t=100 sec\)

\(E=\frac{\varepsilon^{2}}{R} t\)

\(E=\frac{\left(4 \times 10^{-5}\right)^{2}}{2 \times 10^{-6}} \times 100 J\)

\(E=\frac{16 \times 10^{-10} \times 100}{2 \times 10^{-6}} J\)

\(E=0.08 J\)