Question

what will happen when we will pass current through a solenoid

Answer 1

one application of a solenoid is to control the displacement of a plunger, such as in pneumatic valves... solenoid consist of a coil of wire... if a current flows through the wire... a magnetic field B will be build-up around it... this magnetic field is controlled by the amount of current I flowing thru' the coil of wire...
\[B=\mu\times n\times I\]where\[\mu~ is~the~permeability\]\[n=\frac{N}{L},~N~number~of~turns,~and~L~is~length~of~wire\]

Answer 2

... the magnetic field produced by the solenoid will introduce a pushing or pulling force depending on the usage of the plunger in the system... it will displace the position of the plunger...