There are two electric bulbs,$(i)$ marked $60\, W, 220\, V$ and $(ii)$ marked $100\, W, 220\, V$. Which one of them has higher resistance?

$(a)$ What is an electric circuit?
$(b)$ Calculate the number of electrons that flow per second to constitute a current of one ampere. The charge on an electron is $1.6 \times 10^{-19} \ C$.
$(c)$ Draw an electric circuit for studying Ohm's law. Label the circuit components used to measure electric current and potential difference.

What are the conditions under which $Ohm's$ law is not obeyed?

$(a)$ $A$ Nichrome wire of length $L$ and radius $r$ has a resistance of $10 \, \Omega$. How would the resistance of the wire change when:
$(i)$ only the length of the wire is doubled?
$(ii)$ only the diameter of the wire is doubled? Justify your answer.
$(b)$ Why are the elements of electrical heating devices made up of alloys?

Which device works on the heating effect of electric current?

In a household,$5$ tube lights of $40 \text{ W}$ each are used for $5 \text{ hours}$ and an electric press of $500 \text{ W}$ for $4 \text{ hours}$ everyday. Calculate the total energy consumed by the tube lights and press in a month of $30 \text{ days}$.