Discussion Forum

Electric current is measured by tangent galvanometer, the current being proportional to the tangent of the angle $\theta$ of deflection. If the deflection is read as $45^{0}$ and  an error of 1%  is made  in reading it.then  the percentage error in the current  is 

Answer:

Explanation:

According to the given informations   $I\propto \tan\theta$

 So, $\frac{\triangle I}{I}\times 100=sec^{2} \theta \frac{\triangle\theta}{\theta}\times 100$

 at    $\theta=45^{0}.\frac{\triangle \theta}{\theta}\times 100=\frac{\pi}{4}\times\frac{1}{100}\times 100=\frac{\pi}{4}$

 So, percentage error in current is   $\frac{\triangle I}{I}\times 100$

     = $2 \times  \frac{\pi}{4}=\frac{\pi}{2}$