Draw a schematic diagram of an electric circuit consisting of a battery of two cells each of $1.5\, V$,$5\, \Omega$,$10\, \Omega$ and $15\, \Omega$ resistors and a plug key,all connected in series.

What is the cause of resistance?

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?

$(a)$ $A$ 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?

In a Voltaic cell,what is the direction of the flow of electrons in the external circuit?

How can we measure the current in a circuit?