\(\frac{d B}{d x}=-\frac{10^{-3}}{10^{-2}}\)
\(\int_{B_0}^B d B=-\int_0^x 10^{-1} d x\)
\(B-B_0=-10^{-1} x\)
\(B=\left(B_0-\frac{x}{10}\right)\)
Motional emf in \(\mathrm{AB}=0\)
Motional emf in \(\mathrm{CD}=0\)
Motional emf in \(\mathrm{AD}=\varepsilon_1=\mathrm{B}_0 / \mathrm{v}\)
Magnetic field on \(\operatorname{rod} B C B\)
\(=\left(\mathrm{B}_0-\frac{\left(-12 \times 10^{-2}\right)}{10}\right)\)
Motional emf in \(\mathrm{BC}=\varepsilon_2=\left(\mathrm{B}_0+\frac{12 \times 10^{-2}}{10}\right) \ell \times \mathrm{v}\)
\(\varepsilon_{\text {eq }}=\varepsilon_2-\varepsilon_1=300 \times 10^{-7} \mathrm{~V}\)
For time variation
\(\left(\varepsilon_{\text {eq }}\right)^{\prime}=\mathrm{A} \frac{\mathrm{dB}}{\mathrm{dt}}=60 \times 10^{-7} \mathrm{~V}\)
\(\left(\varepsilon_{\text {eq }}\right)_{\text {net }}=\varepsilon_{\text {eq }}+\left(\varepsilon_{\text {eq }}\right)^{\prime}=360 \times 10^{-7} \mathrm{~V}\)
\(\text { Power }=\frac{\left(\varepsilon_{\text {eq }}\right)_{\text {net }}^2}{\mathrm{R}}=216 \times 10^{-9} \mathrm{~W}\)