Questions in Current Electricity

Select	Question
	When a piece of aluminium wire of finite length is drawn through a series of dies to reduce its diameter to half its original value, its resistance will become
	A wire 100 $cm$ long and 2.0 $mm$ diameter has a resistance of 0.7 ohm, the electrical resistivity of the material is
	A certain wire has a resistance $R$. The resistance of another wire identical with the first except having twice its diameter is
	In hydrogen atom, the electron makes $6.6 \times {10^{15}}$ revolutions per second around the nucleus in an orbit of radius $0.5 \times {10^{ - 10}}m$. It is equivalent to a current nearly
	A wire of length 5 $m$ and radius 1$mm$ has a resistance of 1 ohm. What length of the wire of the same material at the same temperature and of radius 2 $mm$ will also have a resistance of 1 ohm
	When there is an electric current through a conducting wire along its length, then an electric field must exist
	Through a semiconductor, an electric current is due to drift of
	In an electrolyte $3.2 \times {10^{18}}$ bivalent positive ions drift to the right per second while $3.6 \times {10^{18}}$ monovalent negative ions drift to the left per second. Then the current is
	A metallic block has no potential difference applied across it, then the mean velocity of free electrons is = absolute temperature of the block)
	The specific resistance of all metals is most affected by