A physical quantity is given as . The percentage error in the measurement of , , , and are , , , and respectively. The percentage error in the measurement of is:
- A
- B
- C
- D
A physical quantity is given as . The percentage error in the measurement of , , , and are , , , and respectively. The percentage error in the measurement of is:
Correct answer:B
Standard Method
Given: and the percentage errors are in , in , in , and in .
Find: The percentage error in .
For multiplication, division, powers, and roots, percentage errors add with their respective powers. Therefore,
Substitute the given values:
Now add all contributions:
Therefore, the percentage error in is . The correct option is B.
Term-wise Error Contribution
Given: depends on , , , and .
Find: Total percentage error in .
The error contribution from each factor is obtained by multiplying the percentage error by the magnitude of its power:
Adding them gives:
Hence, the required percentage error is , so the correct option is B.
Using subtraction for quantities in the denominator is incorrect in error propagation. Percentage errors are added irrespective of whether the quantity is in the numerator or denominator. Add the magnitudes of the contributions instead.
Taking the error contribution of as is incorrect. For a square root, the percentage error is multiplied by , so the contribution is .
Ignoring the powers on and is incorrect. The terms and contribute times and times their percentage errors respectively. Always multiply by the absolute power.
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