Effect of radius changes on electric fields and potential difference?

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SUMMARY

The discussion clarifies the relationship between electric potential and electric fields in the context of radius changes. The formula for electric potential, V = kQ/r, indicates that doubling the radius halves the potential energy due to its inverse proportionality to radius. In contrast, the electric field, described by E = kQ/r², remains unchanged because it is a vector quantity that cancels out when considering equal distances and charges. This distinction highlights the difference between scalar and vector quantities in physics.

PREREQUISITES
  • Understanding of electric potential and electric fields
  • Familiarity with the formulas V = kQ/r and E = kQ/r²
  • Basic knowledge of vector and scalar quantities
  • Concept of proportionality in physics
NEXT STEPS
  • Study the implications of vector quantities in electric fields
  • Explore the concept of electric potential energy in different geometries
  • Learn about the effects of charge distribution on electric fields
  • Investigate the relationship between electric fields and potential differences in capacitors
USEFUL FOR

Physics students, electrical engineers, and anyone interested in understanding the principles of electric fields and potentials in electrostatics.

mirandab17
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Hello!

Okay so I understand that electric potential:

V = kQ/r

...must be influenced by the radius doubling because it would make the potential energy half of what it originally was because of the proportionality law, v is proportional to 1/r.

With electric fields though, how can there possibly be no change? The formula is

E = kQ/r^2

...meaning if should be influenced as well?

The answer is c, btw.
 
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So do the math - calculate the field before and after the change in position.
Note: E is a vector.
 
Oh! Right!

Since E is a vector, and the distance and charges on both sides are equal, then they always simply cancel out to zero. Whereas with electric potential, a scalar quantity, it is not affected by direction, merely magnitude, in which case both are positive, so the radius change will definitely affect it.

Thanks bud!
 
No worries - that "Oh! Right!" feeling is what I was going for :)
 

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