Nichrome Wire, Often Used for Heating Elements, Has Resistivity of 1.0

Multiple Choice

Nichrome wire, often used for heating elements, has resistivity of 1.0 × 10^-6 Ω ∙ m at room temperature. What length of No. 30 wire (of diameter 0.250 mm) is needed to wind a resistor that has 50 ohms at room temperature?

A) 3.66 m
B) 2.45 m
C) 0.61 m
D) 6.54 m
E) 22.4 m