Final answer:
The electromagnetic force can be derived by taking the negative gradient of the field energy function.
Step-by-step explanation:
The field energy for an electromagnetic system is usually related to the electric and magnetic field intensities, and the electromagnetic force can be obtained by the gradient of the potential energy or by considering the Lorentz force, which states that F = q(E + v × B), where F is the force on a charge q, E is the electric field, v is the velocity of the charge and B is the magnetic field.
The electromagnetic force can be derived by taking the negative gradient of the field energy function. In this case, the field energy is given by:
Wf = λ1 + 0.3(λ1 + λ2)² + 5(λ3)^2/7 + x² + x
Taking the negative gradient of this function with respect to position, we can find the expression for the electromagnetic force:
F = -∇Wf
Where ∇ is the del operator.