E Field of Sphere: Find Magnitude at Distance .05m

  • Thread starter Thread starter pyroknife
  • Start date Start date
  • Tags Tags
    Field Sphere
AI Thread Summary
To find the electric field magnitude at a distance of 0.05m from the center of a nonconducting solid sphere with a radius of 0.1m and a uniform volume charge density of 2*10^-6 C/m^3, the correct approach involves using the formula for the electric field inside the sphere. The total charge (Q) was calculated as approximately 8.38e-9 C. The electric field formula for points inside the sphere is E(r) = (1/(4πε₀))(Q/R³) * r. The initial calculation yielded an incorrect value of 30,000 N/C, but the correct electric field at 0.05m is 470 N/C, confirming the necessity of using the appropriate formula for points within the sphere. Understanding the distinction between electric fields inside and outside the sphere is crucial for accurate calculations.
pyroknife
Messages
611
Reaction score
4

Homework Statement



A nonconducting solid sphere of radius (R) .1m has uniform volume charge density (2*10^-6 C/m^3 was calculated and verified accurate). Find the magnitude of the e field at a distance (r) .05m from the sphere's center.

Homework Equations

The Attempt at a Solution


flux=E*4*pi*r^2 = Q/Eo
I calculated Q by multiplying the volume charge density by its volume (4/3)*pi*(.1^3) which got me 8.38e-9 C.

I solved for E=Q/(Eo * 4 * pi * r^2) which got me 30000 N/C. But that answer was 470 N/C. What did i do wrong?
 
Physics news on Phys.org
you have to use the electric field inside the sphere since r=0.05 m is less than the radius
R= 0.1 m. Electric field inside the sphere at a distance r from the center is

E(r)=\frac{1}{4\pi \epsilon_o}\;\frac{Q}{R^3}\;\; r

where Q is the total charge

reference:http://www.phys.uri.edu/~gerhard/PHY204/tsl56.pdf
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top