Which quantity is increased in a step-down transformer?

Transformer is used for-

If the length of a copper wire is increased by twice, then its resistivity will be

If potential difference and current flowing through a wire is increased twice each then electric power :

A fuse is used in main electric supply as a safety device. Which one of the following statements about the fuse is correct?

Which of the following metals is used as filament in lighting bulbs?