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3 years ago

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One wire has a cross-sectional area of 1,250 cmil and a resistance of 7 ohms. A second piece of wire, identical except for cross

-sectional area, has a resistance of 10 ohms. Determine what the cross-sectional area of this second wire is. (Cross-sectional area and resistance are inversely proportional.)

1 answer:

Kruka [31]3 years ago

8 0

Answer:

875 cmil

Explanation:

Cross section area of wire= $A_1=1250 cmil$

Resistance of wire, $R_1=7\Omega$

$R_2=10\Omega$

We have to find the cross sectional area of second wire

We know that

$R=\frac{\rho l}{A}$

According to question

$l_1=l_2=l,\rho_1=\rho_2=\rho$

$R_1=\frac{\rho l}{1250}$

$7=\frac{\rho l}{1250}$ ....(1)

$10=\frac{\rho l}{A}$ ...(2)

Equation (1) divided by equation (2) then, we get

$\frac{7}{10}=\frac{A}{1250}$

$A=\frac{7}{10}\times 1250=875cmil$

Hence, the cross- sectional area of second wire=875 cmil

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