Traditionally,which coloured insulation on wire is used for earthing?

What is the advantage of the third wire of earth connection in domestic appliances?

The diagram below shows a circuit containing a coil wound over a long and thin hollow cardboard tube. Copy the diagram and:
$(i)$ Show the polarity acquired by each face of the solenoid.
$(ii)$ Draw the magnetic field lines of force inside the coil and also show their direction.
$(iii)$ Mention two methods to increase the strength of the magnetic field inside the coil.

Can a freely suspended current-carrying solenoid stay in any direction? Justify your answer. What will happen when the direction of current in the solenoid is reversed? Explain.

Find the minimum rating of fuse that can be safely used on a line on which two $1.1 \, kW$ electric geysers are to run simultaneously. The supply voltage is $220 \, V$. (in $A$)

Define magnetic field. Describe an activity to draw magnetic field lines around a bar magnet from one pole to another pole.