Physics - Error Question with Solution | TestHub

PhysicsErrorMiscellaneousEasy2 minPYQ_2013
PhysicsEasysingle choice

Using the expression2d sin θ=λ, one calculates the values ofdby measuring the corresponding angleθin the range0to90°. The wavelengthλis exactly known and the error inθis constant for all the values ofθ. Asθincreases from0°,

Options:

Answer:
D
Solution:

2d sin θ=λ
d=λ2 sin θ
Differentiate on both the sides,
∂d=λ2∂ cosec θ
∂d=λ2-cosec θ cot θ∂θ
∂d=-λ cos  θ2 sin2 θ∂θ
 θ=increases andλ cos θ2 sin2 θdecreases.
Alternate solution
d=λ2 sin θ
ℓn d=ℓn λ-ℓn 2-ℓn sin θ
Δdd=0-0-1sin θ×cos θΔθ
Fractional error,+d=cot θΔθ
Absolute error,Δd=d cot θΔθ
d2sin θ×cos θsin θ
Δd=cos θsin2 θ

Stream:JEE_ADVSubject:PhysicsTopic:ErrorSubtopic:Miscellaneous
⏱ 2mℹ️ Source: PYQ_2013

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