Two thin metallic spherical shells of radii \( r_{1} \) and \( r_{2}\left(r_{1}

\( \frac{K\left(\theta_{2}-\theta_{1}\right)}{r_{2}-r_{1}} \)

\( \frac{K\left(\theta_{2}-\theta_{1}\right)\left(r_{2}-r_{1}\right)}{4 \pi r_{1} r_{2}} \)

\( \frac{4 \pi K r_{1} r_{2}\left(\theta_{2}-\theta_{1}\right)}{r_{2}-r_{1}} \)

\( \frac{\pi r_{1} r_{2}\left(\theta_{2}-\theta_{1}\right)}{r_{2}-r_{1}} \)