Draw a schematic diagram of a circuit consisting of a cell of $1.5 \, V$, a $10 \, \Omega$ resistor, a $15 \, \Omega$ resistor, and a plug key, all connected in series.

(N/A) To draw the circuit diagram in series, connect the components one after another in a single loop. The circuit includes a cell of $1.5 \, V$, two resistors of $10 \, \Omega$ and $15 \, \Omega$, and a plug key, all joined in a series combination as shown in the diagram.