CBSE Class 10 Science 2026: question 34(a)

Hints

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Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

1. Given: $r=0.01$ cm $=1\times 10^{-4}$ m, $l=1$ cm $=0.01$ m, $R=7\Omega$. Formula: $R=\rho \frac{l}{A}$, so $\rho =\frac{RA}{l}=\frac{R\pi r^2}{l}$

   ½ mark

2. Substituting: $\rho =\frac{7\times \frac{22}{7}\times (10^{-4}{)}^2}{0.01}=\frac{22\times 10^{-8}}{10^{-2}}$

   1 mark

3. $\rho =22\times 10^{-6}\Omega \text{m}=2.2\times 10^{-5}\Omega \text{m}$

   ½ mark

Answer: ρ = 2.2 × 10⁻⁵ Ω m

Revise the chapter

• Chapter: Electricity (notes, formulas, where marks are lost and every past question)
• Topic: Resistance and Resistivity