A bar of silicon is 4 cm long with a circular cross section. If the resistance of the bar is 280 Ω at room temperature, what is the cross-sectional radius of the bar?

r = 17.05 cm

Explanation:

Given that,

Length of silicon bar is 4 cm or 0.04 m

Resistance of the bar is 280 ohms

We know that the resistivity of the silicon is 640 Ωm

We need to find the cross-sectional radius of the bar. Let it is r.

Using definition of resistance of an object. It is given by :

A is area of bar, A = πr²

So,

So, the cross-sectional radius of the bar is 17.05 cm.

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