Electrostatics - sphere electric field

[Agonche]

Homework Statement

Two concentric spheres with radius r1=6cm and r2=10cm are charged with electric charges Q1=-1nC and Q2=0.5nC. Find the intensity of the electric field on distance 5cm and 14 cm from the center of the sphere.

I think they look something like this

Please if anyone knows the solution. write it down.
I just need the start .. the formula.. i can do calculations by myself.

Homework Equations

The Attempt at a Solution

i may be wrong but here's my try
since the first distance d1=5cm
and the sphere sizes are larger so
d1<r1
d1<r2
E1=0
E2=0

there is no electric field inside sferes

what about the distance 14cm

 

[yinx]

Homework Statement

Two concentric spheres with radius r1=6cm and r2=10cm are charged with electric charges Q1=-1nC and Q2=0.5nC. Find the intensity of the electric field on distance 5cm and 14 cm from the center of the sphere.

I think they look something like this

Please if anyone knows the solution. write it down.
I just need the start .. the formula.. i can do calculations by myself.

Homework Equations

The Attempt at a Solution

i may be wrong but here's my try
since the first distance d1=5cm
and the sphere sizes are larger so
d1<r1
d1<r2
E1=0
E2=0

there is no electric field inside sferes

what about the distance 14cm

For E field at 14cm, since this point is outside of the sphere,take the sphere as a point charge and calculate the E-field using E=KQ/R^2 (E-field of point charge)

an alternative view point will be to use gauss law, EA=Q(enclosed)/(epsilon nought)
manipulate the equation and solve for E.