Question

if you switched off an appliance and then the compass needle deflects when bought along the cable.what does it show

Answer 1

the compass needle will show deflection the very second you turn off the current....

this is because the sudden turning off the current sets up an induced emf in the coils of the appliance....this phenomenon is called self induction...

as you switch off the current...the coil opposes the sudden decrease in current(Lenz law) so it sets up an emf in direction opposite to the change...hence causing an field around it...

hence you see the deflection...

If you arent clear with the concept feel free to ask in comments...i will try to clarify to the extent of my knowledge

Answer 2

It shows there is change in magnetic flux......