Who invented the simple battery?

Nichrome is used to make the element of an electric heater. Why?

Name the commercial unit of electrical energy. Convert it into joule. What is the other name of the commercial unit?

$100 \, J$ of heat is produced each second in a $4 \, \Omega$ resistance. Find the potential difference across the resistor. (in $, V$)

What is the formula to find electric power $P$?

$(a)$ Calculate the resistance of the wire using the graph.
$(b)$ How many $176 \,\Omega$ resistors in parallel are required to carry $5\, A$ on a $220\, V$ line?
$(c)$ Define electric power. Derive the relation between power,potential difference,and resistance.