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JEE Main
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Physics
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Mathematics in Physics

JEE Main · Physics · Mathematics in Physics

To determine the density of a solid sphere, its mass is measured as...

To determine the density of a solid sphere, its mass is measured as 10.00 g10.00\text{ g} using an instrument with a least count of 0.01 g0.01\text{ g}. Its diameter is measured as 2.00 mm2.00\text{ mm} using a screw gauge having a pitch of 1 mm1\text{ mm} and 100100 divisions on its circular scale. The maximum percentage error in the calculated density of the sphere is

Options

  1. A0.6%0.6\%
  2. B1.1%1.1\%
  3. C1.6%1.6\%
  4. D3.1%3.1\%

Correct answer

C. 1.6%1.6\%

Step-by-step solution

The least count of the screw gauge is given by:
Least count=PitchNumber of circular scale divisions=1 mm100=0.01 mm\text{Least count} = \dfrac{\text{Pitch}}{\text{Number of circular scale divisions}} = \dfrac{1\text{ mm}}{100} = 0.01\text{ mm}

This least count represents the absolute error in the measurement of the diameter, so ΔD=0.01 mm\Delta D = 0.01\text{ mm}.

The absolute error in mass is the least count of the weighing instrument, so Δm=0.01 g\Delta m = 0.01\text{ g}.

The density ρ\rho of a sphere is given by:
ρ=mV=m43π(D2)3=6mπD3\rho = \dfrac{m}{V} = \dfrac{m}{\dfrac{4}{3}\pi \left(\dfrac{D}{2}\right)^3} = \dfrac{6m}{\pi D^3}

The maximum relative error in density is:
Δρρ=Δmm+3ΔDD\dfrac{\Delta \rho}{\rho} = \dfrac{\Delta m}{m} + 3\dfrac{\Delta D}{D}

Percentage error in mass mm is:
Δmm×100=0.0110.00×100=0.1%\dfrac{\Delta m}{m} \times 100 = \dfrac{0.01}{10.00} \times 100 = 0.1\%

Percentage error in diameter DD is:
ΔDD×100=0.012.00×100=0.5%\dfrac{\Delta D}{D} \times 100 = \dfrac{0.01}{2.00} \times 100 = 0.5\%

Therefore, the maximum percentage error in density is:
\left(\dfrac{\Delta \rho}{\rho} \times 100\right) = 0.1\% + 3(0.5\%) = 0.1\% + 1.5\% = 1.6\%<br><br>Answer:<br><br>Answer:1.6\%
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