Question

i) state & explain ohm's law
ii) define resistivity and its si unit
iiii) what are the advantages of connecting electrical devices in parallel instead of series

Answer 1

if one device stops working and is connected in series than all will stop working but if it's in parallel than other will not stop....
it's the advantage of connecting in parallel

Answer 2

(1) potential difference across the two points of a metallic conductor is directly proportional to current passing through the circuit provided that temperature remains constant
Mathematical expression for Ohm's law :
V is proportional to I

(2) it is defined as the resistance offered by a cube of a material of side 1 m when current flows perpendicular to it's opposite faces
It's S.I unit is ohm metre