Answer:The magnetic field around an electromagnet is just the same as the one around a bar magnet. It can, however, be reversed by turning the battery around. Unlike bar magnets, which are permanent magnets, the magnetism of electromagnets can be turned on and off just by closing or opening the switch.
Answer:
energy per unit charge
Explanation:
EMF is energy per unit charge and has unit joule/ coulomb, where joule is unit of energy and coulomb is the unit of charge.
Answer:
The energy of photon, 
Explanation:
It is given that,
Voltage of anode, 
We need to find the maximum energy of the photon of the x- ray radiation. The energy required to raise an electron through one volt is called electron volt.

e is charge of electron


So, the maximum energy of the x- ray radiation is
. Hence, this is the required solution.