Why moving iron instruments are used on AC and DC supply both?
Why moving iron instruments work on AC and DC supply both but moving coil instruments work only in DC supply only ? 
What is the difference between moving-iron and moving-coil instruments? What is difference between moving coil and moving iron ammeter? What happens when dc supply is given to ac machines? Why is the core of a moving coil galvanometer taken as a soft iron cylinder? Why does a current carrying coil produce magnetic field? What motors are used in railways? AC or DC? Which motor requires both ac and dc supply.? What motors are used in railways? Is AC or DC How does a current-carrying conductor produce a magnetic field when made into a coil? Why are iron and aluminum used to make power cables? Why a mixture of iron and aluminium in making power cables? Why is DC motor not used in home appliances? How hot does moving metal need to be to generate an electromagnetic field? What are applications of DC motors? Why we use ac than dc? Why is high voltage AC used in power transmission lines instead of DC and/or higher current? Can I mix AC and DC current? Chemistry: why does spinning a magnet inside of copper windings create electricty work better than using other metals found in the d block (excluding silver and gold)? What are the differences between a DC motor and an AC motor? What would happen if a DC motor was supplied with AC and vice-versa? It's said that commutators in DC motors or generators convert AC into DC quantity and vice versa. How would it convert DC into AC? What are the main advantages and disadvantages of AC and DC motors, which are majorly used in the industries and why? Why do we excite field winding of an alternator with dc source rather than an ac source? Why does a generator use AC and not DC circuit? Why will a 3 phase AC supply produce a rotating magnetic field only in an induction motor but not in a transformer? What changes have to be made to make AC motor a DC motor or vise versa? In a magnetic crane, a powerful electromagnet is used to lift up the iron material. But when we pass a current through a conductor & bring iron filings near it, they are set in a concentric manner, instead of clinging the conductor. Why? What is the reason for the presence of a single coil and inductor coil in the wattmeter? Does DC flow through conductor? How does electricity move in the human body? AC, DC or some other way?