The heat generated in a circuit is given by $Q\mathit{=}{I}^{2}Rt$, where $I$ is current, $R$ is resistance and $t$ is time. If the percentage errors in measuring $I\mathit{,}\mathit{ }R$ and $t$ are $2\%, 1\%$ and $1\%$, respectively, then the maximum error in measuring heat will be

In the context of accuracy of measurement and significant figures in expressing results of experiment, which of the following is/are correct?

(a) Out of the two measurements $50.14 \mathrm{cm}$ and $0.00025 \mathrm{A}$, the first one has greater accuracy.

(b) If one travels $478 \mathrm{km}$by rail and $397 \mathrm{m}$by road, the total distance travelled is $478 \mathrm{km}$.