Brass scale of a Barometer gives correct reading at 0- C- Coefficient of linear expansion of brass is 18- 10-6- -C- If the barometer reads 76 cm at 20-C -the correct reading is -Hg -18 - 10-5- C-

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Standard XII

Physics

Multiplication & Division of Errors

Brass scale o...

Question

Brass scale of a Barometer gives correct reading at $0^{\circ} C$ . Coefficient of linear expansion of brass is $18 \times 10^{- 6} /^{\circ} C$ . If the barometer reads 76 cm at $20^{\circ} C$ ,the correct reading is ( $γ_{H g} = 18 \times 10^{- 5} /^{\circ} C$ ):

76.426 cm

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75.7cm

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76.642 cm

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76.264 cm

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Solution

The correct option is C 75.7cm
Let the correct reading be $l_{0}$ .
Then reading at $20^{\circ} C = l_{0} (1 + α Δ θ)$
$⟹ l_{0} = \frac{l}{1 + α Δ θ}$
$= 75.7 c m$

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Brass scale of a Barometer gives correct reading at 0∘C. Coefficient of linear expansion of brass is 18×10−6/∘C. If the barometer reads 76 cm at 20∘C ,the correct reading is (γHg=18×10−5/∘C):

The correct option is C 75.7cmLet the correct reading be l0.Then reading at 20∘C=l0(1+αΔθ)⟹l0=l1+αΔθ=75.7cm

Brass scale of a Barometer gives correct reading at $0^{\circ} C$ . Coefficient of linear expansion of brass is $18 \times 10^{- 6} /^{\circ} C$ . If the barometer reads 76 cm at $20^{\circ} C$ ,the correct reading is ( $γ_{H g} = 18 \times 10^{- 5} /^{\circ} C$ ):

The correct option is C 75.7cm
Let the correct reading be $l_{0}$ .
Then reading at $20^{\circ} C = l_{0} (1 + α Δ θ)$
$⟹ l_{0} = \frac{l}{1 + α Δ θ}$
$= 75.7 c m$