Tag: units and measurement: error analysis

Questions Related to units and measurement: error analysis

Are senses reliable for accurate measurement?

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. True

  2. False

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Correct Option: B
Explanation:

Our senses are not reliable for accurate measurement.

Which of the following time measuring devices is most precise?

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. A wall clock

  2. An atomic clock

  3. A digital watch

  4. stop watch

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Correct Option: B
Explanation:

Option $(B)$ is correct because a clock can measure time correctly up to one second. A stopwatch can measure time correctly up to a fraction of a second. A digital watch can measure time up to a fraction of second whereas an atomic clock is the most accurate timekeeper and is based on characteristic frequencies of radiation emitted by certain atoms having a precision of about $1$ second in $300,000$ years. So an atomic clock can measure time most precisely as the precision of this clock is about $1 s$ in $10^{13} s$.

 Students A, B and C measure the diameter of a wire using three different screw gauges of least count  0.01 cm, 0.05 cm and 0.001 cm respectively. Each one makes 10 measurements.The measurements will be more precise for 

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. A

  2. B

  3. C

  4. all

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Correct Option: C
Explanation:

For a screw gauge, the precision in measurement is depends on the least count. The smaller least count will give the more precision. Since student C has measured diameter using screw gauge with smallest least count so the measurement will more precise for student C.   

Students A,B and C measure the diameter of a copper ball using the same screw gauge. A takes 5 readings, B takes 9 readings and C takes 8 readings. The measured value will be most accurate for

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. B

  2. A

  3. C

  4. all

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Correct Option: A
Explanation:

The accuracy is how close the measured value with the true value. The true value is the average value of the measurements. Thus when more number measurements will be taken, the accuracy will be more. Since student B has taken more readings, so the measured value for B will be most accurate.   

In lab one student obtained a weight measurement of $3.2 kg$ for a given substance, but the actual or known weight is $10 kg$, then his measurement is :

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. accurate

  2. not accurate

  3. precised

  4. not presiced

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Correct Option: B
Explanation:

Since the measured value of weight of the substance is far away from the value of actual weight, so the measurement is said to be inaccurate.

 If measurements for a given substance are close to the known value, but the measurements are far from each other, then you have _______ without _______. Fill the appropriate answers.

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. Accuracy, Precision

  2. Precision, Accuracy

  3. This situation is not possible

  4. None of these

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Correct Option: A
Explanation:

Accuracy is defined as the extent upto which a given measurement agrees with the standard value for that measurement whereas the degree to which several measurement provide answer very close to each other is known as precision.
Since the measurements are close to the known value. so these measurements are accurate but these are far from each other, these are not precised.

The mass of an object is measured by two students (true weight is 12 kg)
Student 1: He measures 12 kg
Student 2: She measures 12.5 kg
Measurement of which student is more accurate.

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. Student 1

  2. Student 2

  3. Both are equally accurate

  4. Cannot be compared.

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Correct Option: A
Explanation:

Accuracy defines nearness of a measured value to the standard or true value. Since value measured by student 1 is nearer to the actual value $12 \ kg$ compared to that measured by student 2. So measurement of student 1 is more accurate.

The extent to which a given measurement agrees with the standard value for that measurement is known as :

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. Accuracy

  2. Precision

  3. Accuracy and Precision

  4. None of these

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Correct Option: A
Explanation:

Accuracy is defined as the extent upto which a given measurement agrees with the standard value for that measurement.
For example : Actual weight of the given substance is $10.0 \ kg$ and the measured value of the mass is $9.9 \ kg$. This measurement is said to be accurate.

________ refers to the degree of conformity and correctness of something when compared to a true or absolute value. Fill the appropriate answer.

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. Accuracy

  2. Precision

  3. Accuracy and Precision

  4. None of these

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Correct Option: A
Explanation:

Accuracy is defined as the extent upto which a given measurement agrees with the standard value for that measurement. Accuracy refers to the degree of conformity and correctness of something when compared to a true or absolute value.

_______ refers to a state of strict exactness.Fill the appropriate answer.

physics units and measurement: error analysis accuracy of measurement accuracy and precision accuracy, precision and uncertainty in measurement

  1. Accuracy

  2. Precision

  3. Accuracy and Precision

  4. None of these.

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Correct Option: B
Explanation:

Precision refers to a state of strict exactness.
For example : Let the true weight of given substance is 12 kg.
The values of three measurements obtained by student are 10.1, 10.2 and 10.3. Then the measurements are said to be precise.