Final answer:
To determine the distance required to achieve a specific electric potential from a point charge, the formula V = kQ/r is employed, where V represents the potential desired, k is Coulomb's constant, Q is the charge, and r is the distance from the charge.
Step-by-step explanation:
Calculating Electric Potential Distance
To find the distance from a point charge where the electric potential is a certain value, we use the formula for the electric potential due to a point charge which is V = kQ/r, where V is the potential, k is Coulomb's constant (8.99 × 10⁹ Nm²/C²), Q is the charge, and r is the distance from the charge.
For a charge of 0.91×10⁻⁶ C (or 0.91 micro coulombs) and a potential of 108 V, the equation becomes 108 V = (8.99 × 10⁹)(0.91×10⁻⁶C)/r. Rearranging to solve for r gives r = (8.99 × 10⁹)(0.91×10⁻⁶C)/108 V. Plugging in the values, we calculate the distance r.
Similarly, for a potential of 216 V with the same point charge, we can use the formula again to solve for the new distance or