Question

According to Joule's law of heating, heat produced $H = I^{2}$Rt, where I is current, R is resistance and t is time. If the errors in the measurement of I, R and t are 3%, 4% and 6% respectively then error in the measurement of H is

• A. $\pm$17%
• B. $\pm$16%
• C. $\pm$19%
• D. $\pm$25%

Answer 1

Answer: (B)

$\pm$16%

Answer 2

$H = I^{2}Rt$

$\therefore\frac{\Delta H}{H} \times 100 = \left( \frac{2\Delta I}{I} + \frac{\Delta R}{R} + \frac{\Delta t}{t} \right) \times 100$ $= (2 \times 3 + 4 + 6)\%$

$= 16\%$