Describe SNOW rule for deflection of magnetic needle.

Which electrical phenomenon is responsible for deflection of galvonometer needle in the given figure?

Give the arrangement of magnetic field lines around a straight wire and state the rule to find the direction of magnetic field.

state the rule to determine the direction of a magnetic field produced around a straight conductor carrying current,

When the free ends of the tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason ?