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Joule's law of heating gives us  H = I^2 Rt where I is current R is resistance and t is time . If the error in measurment  I , R and t  are 5 % , 4 % and 8 % respectively  then error in measurment of H is 

Option: 1

\pm 16 \%


Option: 2

\pm 20 \%


Option: 3

\pm 22 \%


Option: 4

\pm 23 \%


Answers (1)

As we have learned

Percentage error in the value of x -

\frac{\Delta x}{x}= \pm \left ( \frac{\Delta a}{a}100+ \frac{\Delta b}{b}100 \right )

(% error in value of a + % error in value of b)

- wherein

\Delta a= absolute error in measurement of a

\Delta b= absolute error in measurement of b

\Delta x= absolute error in measurement of x

 

H = IR^2 t \\\\ \frac{\Delta H}{H} \times 100 = \left [ 2 \frac{\Delta I}{I} + \frac{\Delta R}{R} + \frac{\Delta t}{t}\right ] \times 100 \\\\ = ((2\times 5)+4+8) \% \\ 22 \%

 

Posted by

Ramraj Saini

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