If two mirrors are kept at $${60^ \circ }$$ to each other, then the number of images formed by them is

A wire when connected to $$220$$ $$V$$ mains supply has power dissipation $${P_1}.$$ Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is $${P_2}.$$ Then $${P_2}:{P_1}$$ is

If $${\theta _1},$$ is the inversion temperature, $${\theta _n}$$ is the neutral temperature, $${\theta _c}$$ is the temperature of the cold junction, then

The mass of product liberated on anode in an electrochemical cell depends on (where $$t$$ is the time period for which the current is passed).