On which principle does an electric generator work?

The diagram below shows two ways of connecting three bulbs $A, B$ and $C$ to a $220 \,V$ main in a room. Name the two arrangements. Which of them would you prefer for household electricity? Give two reasons.

$(a)$ What is meant by a 'magnetic field'?
$(b)$ How is the direction of magnetic field at a point determined?
$(c)$ Describe an activity to demonstrate the direction of the magnetic field generated around a current-carrying conductor.
$(d)$ What is the direction of the magnetic field at the centre of a current-carrying circular loop?

The strength of the magnetic field of a solenoid does not depend upon:

With the help of which law or rule can the direction of a magnetic field be known?

If the direction of current is reversed,the direction of magnetic field is also reversed.