- #1

Saptarshi Sarkar

- 99

- 13

- Homework Statement
- Calculate the total charge of an unknown charge distribution for which the electric field is E=q/r^2 e^(-4r) r ̂

- Relevant Equations
- E.A = q/ε0

∇·E = ρ/ε0

I first tried to use the Gauss' law equation E.A = q/ε0 to find the total charge enclosed. The answer came out to be q(enclosed) = 4

Next, I tried the equation ∇·E = ρ/ε0, calculated rho to be -4qε0e^(-4r)/r^2 and total charge to be -4

Why are the answers different although both are derived from Gauss' law? What did I do wrong?

**π**qε0e^(-4r). So for r approaching infinity, q(enclosed) approached 0.Next, I tried the equation ∇·E = ρ/ε0, calculated rho to be -4qε0e^(-4r)/r^2 and total charge to be -4

**π**qε0.Why are the answers different although both are derived from Gauss' law? What did I do wrong?