Question

Charge is uniformly distributed throughout a spherical insulating volume of radius R = 4.00 cm. The charge per unit volume is
ис
- 8.15 Find the magnitude of the electric field at r = 2.00 cm. Enter a positive number if the field points radially out and
negative if the field points radially in.

Answer 1

-8.67× 10^6 N/C

The Electric Field is defined as force per unit charge.

E = Q/ 4π£r2

Qv= −6.5 μCm3

Qv = Q/ V= Q/ 4/3 πr3

Hence Q = 4/3 πr3 × Qv

Hence E = 4/3 πr3 × Qv / 4π£r2= Qvr/3£

−6.5 μ × 4/ 3×8.854 ×10^-12

-6.5 × 4 × 10^6/3 = -8.67× 10^6 N/C

Note: £ = 8.854×10^-12m/F

is the permittivity of free space

Qv is the charge per unit volume

V is volume and volume