A metal has a very large number of free electrons and a non$-$metal very less number of free electrons.

Calculate the equivalent resistance in the combination shown in figure below

Name and define $SI$ unit of resistance. Calculate the resistance of a resistor if the current flowing through it is $200\, mA$, when the applied potential difference is $0.8\, V$.

$(a)$ Define potential difference between two points in a conductor.

$(b)$ Name the instrument used to measure the potential difference in a circuit. How is it connected ?

$(c)$ A current of $2\, A$ passes through a circuit for $1$ minute. If potential difference between the terminals of the circuit is $3 \,V,$ what is the work done in transferring the charges ?

Give an example of a metal which is the best conductor of heat.

$(a)$ What is the total resistance of $n$ resistors each of resistance ' $R^{\prime}$ connected in

$(i)$ series ?

$(ii)$ parallel ?

$(b)$ Calculate the resultant resistance of $3$ resistors $3\, \Omega, 4\, \Omega$ and $12\, \Omega$ connected in parallel.