Define a solenoid. How is it different from a coil?

• A
  $A$ solenoid is a single loop of wire,while a coil has many loops.
• B
  $A$ solenoid is a long cylindrical coil of many turns of insulated copper wire,whereas a coil is a general term for any number of turns.
• C
  $A$ solenoid produces a non-uniform magnetic field,while a coil produces a uniform magnetic field.
• D
  There is no difference between a solenoid and a coil.