What happens to the resistance of a conductor when the length of the conductor is reduced to half?

$A$ wire of resistance $5 \, \Omega$ is bent in the form of a closed circle. What is the resistance between two points at the ends of any diameter of the circle?

What is the resistance of an electric arc lamp,if the lamp uses $20\, A$ when connected to a $220\, V$ line?

Three $2\,\Omega$ resistors,$A$,$B$,and $C$,are connected as shown in the figure. Each of them dissipates energy and can withstand a maximum power of $18\,W$ without melting. Find the maximum current (in $A$) that can flow through the circuit such that none of the resistors melt.

Derive an expression for equivalent resistance when three resistors of resistance $R_{1}, R_{2}$ and $R_{3}$ are connected in parallel.

Elements of electric toasters and electric irons are made of an alloy rather than a pure metal. Give two reasons to justify the statement.