A copper wire has diameter 0.5 mm and resistivity of \( 1.6 × 10^-8 \Omega m. \) What will be the length of this wire to make its resistance 10 \(\Omega \)? How much does the resistance change if the diameter is doubled?
Answer :
Area of cross-section of the wire, A =\(\pi \) (d/2) 2
Diameter= 0.5 mm = 0.0005 m
Resistance, R = 10 \(\Omega \)
We know that
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