'A wire of uniform cross-sectional area 'A' and length 'L' is cut into two equal parts. The resistance of each part becomes.
Correct answer: B. Half
- A. Double
- B. Half
- C. four time
- D. Eight time
Explanation
When a wire with uniform cross-sectional area ( A ) and length ( L ) is cut into two equal parts, the resistance of each part becomes ( R' ). The resistance ( R ) of a conductor is given by the formula: R = ρ L/Awhere ( ρ ) is the resistivity of the material. When the wire is cut into two equal parts, the length ( L ) is halved (L/2), so the new resistance ( R' ) of each part is: R' = ρ (L/2)/A = 1/2 ρ L/A = 1/2 R or R/2Therefore, the resistance of each part becomes half of the original resistance.
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About Resistance and Resistivity
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
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