Determine the force in the spring CD in the relay

Get the book here: https://amzn.to/2py6FIn More videos: http://www.forthesakeofeducation.com Become my official student:   / daxterbels   The relay regulates voltage and current. Determine the force in the spring CD, which has a stiffness of k = 120 N/m, so that it will allow the armature to make contact at A in figure (a) with a vertical force of 0.4 N. Also, determine the force in the spring when the coil is energized and attracts the armature to E, figure (b), thereby breaking contact at A.