According to the NCERT text (Section 3.10), the terminal voltage ($V$) across a cell when current ($I$) is drawn from it is given by the formula $V = \varepsilon - Ir$, where $\varepsilon$ is the EMF and $r$ is the internal resistance. Substituting the given values: $V = 10 \text{ V} - (0.5 \text{ A} \times 3 \ \Omega) = 10 - 1.5 = 8.5 \text{ V}$. This question corresponds directly to Exercise 3.2 in the textbook , .