Final answer:
To find the electric field at a point outside the surface of the sphere, use the formula E = k * (Q / r²). For part (a), the magnitude of the electric field at a point outside the surface of the sphere is approximately 1.168 x 10⁶ N/C. For part (b), the electric field inside a uniformly charged sphere is zero, so the magnitude of the electric field at a point inside the sphere, 0.100 m below the surface, is zero.
Step-by-step explanation:
To find the electric field at a point outside the surface of the sphere, we can use the formula:
E = k * (Q / r²)
where E is the electric field, k is the electrostatic constant, Q is the net charge on the sphere, and r is the distance from the center of the sphere to the point.
For part (a), we have Q = 0.250 nC and r = 0.100 m + 0.450 m = 0.550 m. Plugging these values into the formula, we get:
E = (9.0 x 10⁹ Nm²/C²) * (0.250 x 10⁻⁹ C) / (0.550 m)²
Solving this equation, we find that the magnitude of the electric field at the point outside the surface of the sphere is approximately 1.168 x 10⁶ N/C.
For part (b), the electric field inside a uniformly charged sphere is zero. Therefore, the magnitude of the electric field at a point inside the sphere, 0.100 m below the surface, is zero.