i will mark you as brainliest if you answer correctly      (a) an electric heater coil is connected to a 220v source. if the resistance of the    heater coil is 220ω, find the current.         (b) describe an activity with necessary electric circuit to study the factors on which the resistance of a conducting wire depends.

(A) We can solve the problem by using Ohm's law, which states:

where
V is the potential difference across the electrical device
I is the current through the device
R is its resistance
For the heater coil in the problem, we know  and , therefore we can rearrange Ohm's law to find the current through the device:


(B) The resistance of a conductive wire depends on three factors. In fact, it is given by:

where
is the resistivity of the material of the wire
L is the length of the wire
A is the cross-sectional area of the wire
Basically, we see that the longer the wire, the larger its resistance; and the larger the section of the wire, the smaller its resistance.