Solved 2022 Semester 2 Question Paper ICSE Class 10 Physics — Question 15

(a) Given, R = 2Ω

⇒ ρ$\dfrac{\text{l}}{\text{A}}$ = 2Ω

Let new resistance be R'.

New length = $3\text{l}$

New Area = $\dfrac{\text{A}}{3}$

∴ R' = ρ$\dfrac{\text{3l}}{\dfrac{\text{A}}{3}}$

= ρ$\dfrac{\text{9l}}{\text{A}}$

= 9R = 9 × 2 = 18Ω

Hence, new resistance = 18Ω

(b) Specific resistance of the wire remains unchanged since it does not depend on the dimensions of the wire. It is the characteristic property of the substance.