Answer:
The curl is 
Explanation:
Given the vector function

We can calculate the curl using the definition

Thus for the exercise we will have

So we will get

Working with the partial derivatives we get the curl

Answer:
The value of third charge is 0.8μC.
Explanation:
Given that.
Magnitude of net force=4.444 N
According to figure,
Suppose, First charge = 2.4 μC
Second charge = 6.2 μC
Distance r₁ = 9.8 cm
Distance r₂ = 2.1 cm
We need to calculate the value of r
Using Pythagorean theorem

Put the value into the formula


We need to calculate the force
Using formula of force

Force F₁₂,



Force F₂₃,

We need to calculate the value of third charge





Hence, The value of third charge is 0.8μC.