Spherical cavity electric field

AI Thread Summary
A positive charge of 2800.00 C is uniformly distributed over a sphere with a radius of 6.00 m, and a spherical cavity with a radius of 3.00 m is cut out, removing some charge. The electric field at point P, located 19.00 m from the center of the original sphere, is calculated using the principle of superposition, subtracting the electric field of the smaller sphere from that of the larger sphere. The charge of the smaller sphere is determined to be 3500 C through proportional calculations. The user is seeking assistance in resolving discrepancies in their calculations for the electric field magnitude.
GravityGirl
Messages
28
Reaction score
0
A positive charge Q = 2800.00 C is uniformly distributed over the volume of a sphere of radius R = 6.00 m. Suppose a spherical cavity of radius R/2 is cut out of the solid sphere, the center of the cavity being a distance R/2 from the center of the original solid sphere (see figure). The cut-out material and its charge are discarded. What is the magnitude of the electric field produced by this new charge distribution at point P, a distance r = 19.00 m from the center of the original sphere?


so i am going to use the principle of superposition

E=Ebigsphere-Elittlesphere

inorder to find E i must find the charge and i can do so by using porportions

Qb/Vb=Ql/Vl

that is 28000/904.7787=Ql/113.0973 and Ql=3500

so i am going to use the formula E=KQ/R^2 for both big a little spheres

and i have E=(K28000/19^2)-(K3500/16^2)

with this i am not getting the right solution...please help me find where i am going wrong
 
Physics news on Phys.org
Looks OK to me. Where is point P with respect to the two spheres? (Since we don't have the diagram, it's up to you to describe it carefully.)
 
did you ever figure this out?
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top