Carefull measurement of the electric field at the surface of a black box indicates that the net outwards flux through the surface of the box is `8.0xx10^(3) Nm^(2) //C `
What is the net charges inside the box?
If the net outwards flux through the surface of the were zero ,could you concide that there were no charges inside the box? Why or why not?

Explanation

` because ` Net outwards flux `phi _E =8.0xx 10^(3) Nm^(2) //C `
From the mathematical expression of Gauss. theorem `phi_E=(q)/(in_0) , ` we find that
Net charges inside the box `q =phi _E. in _0 =8.0 xx 10 ^(3) xx 8.55 xx 10^(-12) C `
` =7.08 xx 10^(-8) C = 0.07 muC .`
If the net outwards flux through the surface of the box were zero than in accordance with Gaus theorem we conclude that the net charge inside the box were zero. It means that either no charges we present in the box or charges were present inside the box but their algebraic sum was zero.