A students records the initial length l, change in temperature ∆T an

1.	A students records the initial length l, change in temperature ∆T and change in length ∆l of a rod as follows :If the first observation is correct, what can you say about observation 2, 3 and 4?
Answer» \(\alpha=\frac{ΔI}{IΔT}\) From I observation, \(\alpha=\frac{4\times10^{-4}}{2\times10}\) \(=2\times10^{-5}C^{-1}\) For II, observation Δl=\(\alpha/ΔT \) = 2 × 10^-5 × 1 × 1 = 2 × 10^-4 ≠ 4 × 10^-4 m For III, observation Δl=\(\alpha/ΔT \) = 2 × 10^-5 × 2 × 20 = 8 × 10^-4 m = 2 × 10^-4 m For IV, observation Δl=\(\alpha/ΔT \) = 2 × 10^-5 × 3 × 10 = 6 × 10^-4 m = 6 × 10^-4 m Therefore, IV observation is correct and II, III are wrong

A students records the initial length l, change in temperature ∆T and change in length ∆l of a rod as follows :If the first observation is correct, what can you say about observation 2, 3 and 4?

Answer»

\(\alpha=\frac{ΔI}{IΔT}\)

From I observation,

\(\alpha=\frac{4\times10^{-4}}{2\times10}\)

\(=2\times10^{-5}C^{-1}\)

For II, observation Δl=\(\alpha/ΔT \)

= 2 × 10^-5 × 1 × 1

= 2 × 10^-4 ≠ 4 × 10^-4 m

For III, observation

Δl=\(\alpha/ΔT \)

= 2 × 10^-5 × 2 × 20

= 8 × 10^-4 m

= 2 × 10^-4 m

For IV, observation

Δl=\(\alpha/ΔT \)

= 2 × 10^-5 × 3 × 10

= 6 × 10^-4 m = 6 × 10^-4 m

Therefore, IV observation is correct and II, III are wrong