$(a)$ 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 the potential difference between the terminals of the circuit is $3 \, V$, what is the work done in transferring the charges?

$(a)$ Electric potential difference between two points in an electric circuit carrying current is defined as the work done to move a unit positive charge from one point to the other.
$(b)$ The instrument used to measure potential difference is a Voltmeter. It is always connected in parallel across the points between which the potential difference is to be measured.
$(c)$ Given: Current $(I) = 2 \, A$, Time $(t) = 1 \, \text{minute} = 60 \, s$, Potential difference $(V) = 3 \, V$.
First, calculate the total charge $(Q)$ transferred: $Q = I \times t = 2 \, A \times 60 \, s = 120 \, C$.
Now, calculate the work done $(W)$ using the formula $W = V \times Q$: $W = 3 \, V \times 120 \, C = 360 \, J$.
Thus, the work done is $360 \, J$.