An electric heater rated $600 \ W$ operates $6$ hours per day. Find the cost to operate it for $30$ days at ₹ $3.00$ per unit.

Give reasons for the following:
$(i)$ Tungsten is used almost exclusively for the filament of electric lamps.
$(ii)$ Why do we use copper and aluminium wires for the transmission of electric current?

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

Draw a circuit diagram for a circuit consisting of a battery of five cells of $2 \text{ V}$ each, a $5 \, \Omega$ resistor, a $10 \, \Omega$ resistor, and a $15 \, \Omega$ resistor, an ammeter, and a plug key; all connected in series. Also, connect a voltmeter to record the potential difference across the $15 \, \Omega$ resistor and calculate:
$(i)$ the electric current passing through the above circuit and
$(ii)$ the potential difference across the $5 \, \Omega$ resistor when the key is closed.

What is the electrical resistivity of a material? What is its $SI$ unit? Describe an experiment to study the factors on which the resistance of a conducting wire depends.

From the listed electrical devices,which releases heat energy that is not appreciated?