Electromagnet in the escape room

 

Well we did escape from Leicester in the end. In the escape room, you have to solve clues to find number codes to enter into terminals. If you get it right, a box pops open with more clues. Turns out the doors are held shut by electromagnets so entering the correct code must turn the current off. The is a compression spring which must have a weaker force than the electromagnet which then provides the resultant force to push the door open.