An electric heater rated $1200 \ W$ operates $2 \ h$ per day. Find the cost of the energy required to operate it for $30$ days at ₹ $5.00$ per unit.

The following table provides the resistivity of three samples:

Sample	$A$	$B$	$C$
Resistivity	$1.6 \times 10^{-8} \Omega \cdot m$	$5.2 \times 10^{-8} \Omega \cdot m$	$100 \times 10^{-6} \Omega \cdot m$

Which of them is suitable for heating elements of electrical appliances and why?

If $1 \text{ ampere}$ electric current passes through a conductor,how many electrons will pass per second?

How many joules are there in one kilowatt-hour?

Study the following circuit and answer the following questions:
$(i)$ State the type of combination of the two resistors in the circuit.
$(ii)$ How much current would flow through:
$(a)$ $10 \, \Omega$ resistor and
$(b)$ $15 \, \Omega$ resistor?
$(iii)$ What would be the ammeter reading?

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