In a Voltaic cell,what is the positive electrode (cathode) made of?

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

$A$ student carries out an experiment and plots the $V-I$ graph of three samples of nichrome wire with resistances $R_1, R_2$ and $R_3$ respectively (Figure). Which of the following is true?

If a wire of resistance $R$ is melted and recast to half of its length,then the new resistance of the wire will be

What are the factors on which the resistance of a conductor depends?

An electric oven hot plate is connected to a $200 \, V$ line. It has two resistance coils $A$ and $B$,each of $30 \, \Omega$,which may be used separately,in series,or in parallel. Find the value of the current required in each of the three cases.