Which device uses direct current $(DC)$?

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.

$(a)$ Describe an activity to show the pattern of magnetic field lines of a bar magnet,with the help of a cardboard piece and iron filings.
$(b)$ Compare the magnetic field of a bar magnet with that of a current-carrying solenoid with the help of a figure.

What does the direction of the thumb indicate in the Right-Hand Thumb Rule? In what way is this rule different from Fleming's Left-Hand Rule?

What are magnetic field lines? How is the direction of magnetic field at a point determined? Mention two important properties of magnetic field lines.

Give the direction of induced current in the following figure: