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Question 1 - MCQ questions - Chapter 12 Class 10 - Electricity (Term 2)

Last updated at May 10, 2022 by

A cylindrical conductor of length ‘l’ and uniform area of cross section ‘A’ has resistance ‘R’. The area of cross section of another conductor of same material and same resistance but of length ‘2l’ is

(a) A/2

(b) 3A/2

(c) 2 A

(d) 3 A

 

Answer:

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Transcript

Extra Question A cylindrical conductor of length l and uniform area of cross section A has resistance R. Another conductor of length 2l and resistance R of the same material has area of cross section (a) A/2 (b) 3A/2 (c) 2 A (d) 3 AGiven Length of the conductor = l Area of cross-section = A Resistance of the conductor = R Let the resistivity of the conductor = 𝜌 We know that, R = 𝜌 𝑙/𝐴 ∴ A = 𝜌𝑙/𝑅 New Conductor Given, Length of other conductor = l2 = 2l Resistance of the conductor = R Since the material is same, Resistivity of the conductor = 𝜌 Now, R = 𝜌 𝑙_2/𝐴_2 R = 𝜌 (2l) × 1/𝐴_2 A2 = (𝜌 (2𝑙))/𝑅 A2 = 2((𝜌 𝑙)/𝑅) A2 = 2 A ∴ (c) is correct

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