Final answer:
Charges placed inside a metallic cavity do not affect outer charges and vice versa due to the property of conductors in static equilibrium. The electric field inside the conductor is zero, causing induced charges to redistribute themselves accordingly. This phenomenon ensures that the outer charges are unaffected by the charges placed inside the metallic cavity.
Step-by-step explanation:
A charge placed inside a metallic cavity has no effect on outer charges and vice versa due to the property of conductors in static equilibrium.
When a charge is placed inside a conductor, the excess charges on the conductor redistribute themselves such that the electric field inside the conductor is zero. This means that any charges placed inside a metallic cavity will induce an equal and opposite charge distribution on the inner surface of the cavity, while the outer charges remain unaffected.
Similarly, if a charge is placed outside a conductor with a cavity, the induced charges on the conductor will reside on the outer surface, leaving the inner surface of the cavity free of charge.