If a circular loop is made of $6$ closely wound turns instead of a single turn,the magnetic field produced at the center of the loop becomes $.........$ times stronger.

$A$ soft iron bar is introduced inside a current-carrying solenoid. The magnetic field inside the solenoid:

$(a)$ Draw a schematic labelled diagram of a domestic wiring circuit which includes $(i)$ a main fuse,$(ii)$ a power meter,$(iii)$ one light point,and $(iv)$ a power plug.
$(b)$ Why is it necessary to connect an earth wire to electric appliances having metallic covers?

An alpha particle (positively charged particle) enters a magnetic field at a right angle to it,as shown in the figure. Explain the direction of the force acting on the alpha particle with the help of a relevant rule.

Why are magnetic field lines closed curves?

It is established that an electric current through a metallic conductor produces a magnetic field around it. Is there a similar magnetic field produced around a thin beam of moving $(i)$ alpha particles,$(ii)$ neutrons? Justify your answer.