The units of resistance are ampere.

What is potential difference? Is it a scalar quantity or a vector quantity? Give its $SI$ units.

State Ohm's law. How can it be verified experimentally? Does it hold good under all conditions? Comment.

$(a)$ What material is used in making the filament of an electric bulb?
$(b)$ Name the characteristics which make it suitable for this.

$A$ cell,a resistor,a key and an ammeter are arranged as shown in the circuit diagrams of the figure. The current recorded in the ammeter will be

Define one watt.