A charge of 5 uC is placed at the center of a cube of side 10 cm. The flux through one face is:

Electric field at a point due to a uniformly charged infinite conducting plane is E. If two such planes are placed parallel to each other with opposite charges, the field between them is:

A spherical shell of radius R has charge Q uniformly distributed. The field at r = R/2 (inside) is: <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 400 160" style="max-width:400px;margin:0.5em auto;display:block;"> <title>Charged spherical shell with point at r = R/2 inside</title> <rect width="400" height="160" fill="#faf9f5" rx="8"/> <circle cx="200" cy="80" r="60" fill="none" stroke="#c6613f" stroke-width="2"/> <text x="200" y="16" text-anchor="middle" font-size="10" fill="#c6613f" font-family="sans-serif">+Q (on surface)</text> <circle cx="200" cy="80" r="30" fill="none" stroke="#788c5d" stroke-width="1.2" stroke-dasharray="4,3"/> <text x="240" y="65" font-size="9" fill="#788c5d" font-family="sans-serif">r=R/2</text> <circle cx="200" cy="80" r="3" fill="#14140f"/> <text x="200" y="85" text-anchor="middle" font-size="9" fill="#788c5d" font-family="sans-serif" font-weight="bold">E=0</text> <text x="200" y="150" text-anchor="middle" font-size="10" fill="#14140f" font-family="sans-serif">No enclosed charge → E = 0 inside shell</text> </svg>

The electric field at distance r from the center of a uniformly charged solid sphere (r < R) is E1, and at the surface is E2. The ratio E1/E2 is:

A Gaussian surface encloses charges +3Q, -Q, and +2Q. The total flux through the surface is: