Calculate the magnitude of the electric field inside the solid at a distance of 9.20 cmcm from the center of the cavity. Express your answer with the appropriate units.

A point charge of -2.14uC  is located in the center of a spherical cavity of radius 6.55cm  inside an insulating spherical charged solid. The charge density in the solid is 7.35×10−4 C/m^3.

a) Calculate the magnitude of the electric field inside the solid at a distance of 9.20cm  from the center of the cavity.  

Express your answer with the appropriate units.

==7.3  × 10⁻⁵N/C

Explanation:

A point charge ,q = -2.14uC = - 2.14 × 10⁻⁶

cavity of radius , r = 6.55cm = 6.55 × 10⁻²m

charge density in the solid = 7.35×10⁻⁴ C/m³

Distance from the center of the cavity,R = 9.20cm = 9.2 × 10⁻²m

Volume of shell of charge =

Charge on the shell ,Q = V × d

Q = 4.1888 × ((9.2 × 10⁻²)³ - (6.55 × 10⁻²)³) × 7.35 × 10⁻⁴

Q = 1.47 × 10⁻⁶N/C

Electric field at 9.2× 10⁻²m due to shell

E1 = kQ/R²

= 1.563 × 10⁻⁶N/C

Electric field at 9.2 × 10⁻²m due to q at center

E2

= 2.276 × 10⁻⁶N/C

magnitude of the electric field inside the solid at a distance of 9.50cm from the center of the cavity

= E2- E1

= (2.276 × 10⁻⁶) - (1.563 × 10⁻⁶)N/C

= 0.73 × 10⁻⁶N/C

= 7.3  × 10⁻⁵N/C

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it