Question

the power in an electrical circuit for a current of 5+ or -0.4a and voltage 10+ or -0.2v is measured at 10% error.to measure the power at 5% error the current should be measured at an error of

Answer 1

Explanation:

5+ or -0.4a and voltage 10+ or -0.2v is measured at 10% error.to measure the power at 5% error the current should be measured at

Answer 2

The error of current measured at 5%  power error is 3%.

Step by Step Explanation-

Given : I (current) = 5 ± 0.4 A

          : V (voltage) = 10 ± 0.2 V

          : Power measured at error= 10%

To be found: % error of current at 5% power error.

Formula used: We know,

$P= V. I$

We will first find out error % of current I at 10% error of power P:

Using error % formula-

$\frac{del P}{P} . 100 = \frac{del V}{V} .100 + \frac{del I}{I} .100$

where, $del V$ = ΔV = 0.2

$V= 10$

$del I=$ ΔI = 0.4

$I$= 5

$\frac{del P}{P}= 10%$

∴Putting the values:

$10 = \frac{0.2}{10} . 100 + \frac{0.4}{5} . 100$

⇒$10 = 2 + 8$

⇒ at 10% error of P there is error of 8% of I

∴ at 5% error of P=

$5 = 2 + x$

⇒$x= 5-2$

⇒$x = 3$

∴ at 5% error of power P, there is a 3 % error of current.

Hence, the error of current measured at 5%  power error is 3%.