Calculate Charge: Find Q at Center of Hollow Sphere of Radius 20 cm

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Homework Help Overview

The problem involves calculating the charge Q located at the center of a hollow conducting sphere with a radius of 20 cm, given specific electric field values both outside the sphere and at a certain point within the context of electrostatics.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between the electric field values and the charge distribution, questioning the implications of the electric field decreasing from 500 N/C to 100 N/C after introducing charge Q. Some participants seek clarification on the problem statement and the significance of the terms used.

Discussion Status

The discussion has progressed with participants clarifying the problem statement and exploring the implications of the electric field changes. Some guidance has been offered regarding the application of Gauss's law to analyze the situation, although no consensus has been reached on the final value of charge Q.

Contextual Notes

There is a noted ambiguity regarding the reference to the electric field of 100 N/C and its implications for the charge configuration. The original poster expressed difficulty in determining charge Q due to the lack of information about the solid sphere's radius.

austin007
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The e-field just outside the surface of a hollow conducting sphere of radius 20 cm is 500 N/C and is directed outward. Q is located at the center of the sphere. It is noted that the e-fields is still directed out ward with a magnitude of 100 N/C. What is the magnitude and sign of the unknown charge Q?

I can only find total charge which is 2.225nC. I can't get Q coz radius of the solide sphere is unknown. Pls help
 
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Can you please state the problem completely, exactly as it was given. I don't understand what the field 100 N/C refers to.
 
The electric field just outside the surface of a hollow conducting sphere of radius 20 cm is 500 N/C and is directed outward. An unknown charge Q is then located at the center of the sphere. It is noted that the electric field is still directed outward but its magnitude has decreased to 100 N/C. What is the magnitude and sign of the unknown charge Q?

This is the complete question as it is stated.
 
austin007 said:
The electric field just outside the surface of a hollow conducting sphere of radius 20 cm is 500 N/C and is directed outward.
OK. That should tell you the charge on the conducting shell.
An unknown charge Q is then located at the center of the sphere.
Ah... that additional word "then" makes all the difference!
It is noted that the electric field is still directed outward with a magnitude of 100 N/C.
Now that you've added charge Q, how does the net charge within the gaussian surface (taken just outside the sphere) change?

Apply Gauss's law twice.
 
Last edited:
thanks I understood finally...
 

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