Can I use WD40 to remove rust from my electric hob plate?
I would keep the WD40 as far away from food and food preparation equipment as possible. The MSDS (Material Safety Data Sheet) for WD-40 as published by the manufacturer states:

Emergency Overview:

DANGER!  Harmful or fatal if swallowed.  May cause eye irritation.  Avoid eye contact. Use with adequate 
ventilation.