A thermometer bulb has volume 10⁻⁶ m³ and cross-section of the stem is 0.002 cm². The bulb is filled with mercury at 0. If the thermometer reads temperature as 100, then the length of mercury column is (coefficient of cubical expansion of mercury = 18 × 10⁻⁵/) (a) 90 cm (b) 9 mm (c) 9 cm (d) 0.9 mm

Answer: (c). Δ V=VγΔ T=10⁻⁶×18×10⁻⁵×100=1.8×10⁻⁸ m ³ A=0.002 cm ²=2×10⁻⁷ m ² l=(Δ V)/(A)=1.8×10⁻⁸2×10⁻⁷=0.09 m So the answer is (c) 9 cm.

A thermometer bulb has volume 10⁻⁶ m³ and cross-section of the stem… | MHT CET 2025 (23 Apr, Shift 1)

Q17MHT CET 2025 · 23 APR · SHIFT 1Medium

Thermometry & Thermal Expansion

A thermometer bulb has volume $10^{-6}\text{ m}^3$ and cross-section of the stem is $0.002\text{ cm}^2$ . The bulb is filled with mercury at $0^\circ\text{C}$ . If the thermometer reads temperature as $100^\circ\text{C}$ , then the length of mercury column is (coefficient of cubical expansion of mercury $= 18 \times 10^{-5}/^\circ\text{C}$ )

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Answer: (c)

$\Delta V=V\gamma\Delta T=10^{-6}\times18\times10^{-5}\times100=1.8\times10^{-8}$ m $^3$
$A=0.002$ cm $^2=2\times10^{-7}$ m $^2$
$l=\frac{\Delta V}{A}=\frac{1.8\times10^{-8}}{2\times10^{-7}}=0.09$ m
So the answer is (c) 9 cm.

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Thermometry & Thermal Expansion question from MHT CET 2025 (23 Apr, Shift 1)

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