Define a random error .

A random error causes unpredictable fluctuations in readings due to uncontrollable factors, such as changing environmental conditions.

Define a systematic error .

A systematic error arises from faulty instruments or a flawed method , is repeated in every reading, and affects the accuracy of results.

How can random errors be reduced?

Repeat the measurements several times and calculate a mean average .

How can systematic errors be reduced?

Recalibrate the instrument, or correct or adjust the technique being used.

Define a zero error .

A zero error is a systematic error in which an instrument gives a non-zero reading when the true reading should be zero .

Distinguish between precision and accuracy .

Precision : how close repeated measurements are to each other Accuracy : how close a measurement is to the true value

Random errors affect the .......... of measurements, causing a wider spread of results about the mean.

Random errors affect the precision of measurements, causing a wider spread of results about the mean.

True or False? Repeating a measurement and averaging reduces systematic error.

False. Repeating and averaging reduces random error. Systematic error is reduced by recalibrating the instrument or correcting the method.

Uncertainty is the range of values around a measurement within which the true value is expected to lie; it is an estimate .

State the three ways in which uncertainty can be represented.

Absolute uncertainty — a fixed quantity Fractional uncertainty — a fraction of the measurement Percentage uncertainty — a percentage of the measurement

What is the uncertainty in a single reading (e.g. from a voltmeter), and in a measurement (e.g. from a ruler)?

Reading : ± half the smallest division Measurement : at least ± one smallest division

How do you combine uncertainties when adding or subtracting quantities, and when multiplying or dividing them?

Adding or subtracting : add the absolute uncertainties Multiplying or dividing : add the percentage uncertainties

When a measurement is raised to a power, you .......... its percentage uncertainty by that power.

When a measurement is raised to a power, you multiply its percentage uncertainty by that power.

True or False? An uncertainty and an error are the same thing.

False. An error is a difference from the true value caused by the equipment or method; an uncertainty is the estimated range within which the true value is expected to lie.

A LevelPhysicsCambridge (CIE)Flashcards1. Physical Quantities & UnitsErrors & Uncertainties

Errors & Uncertainties (Cambridge (CIE) A Level Physics): Flashcards

Exam code: 9702

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FrontErrors & Uncertainties
Define a random error.

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Cards in this collection (16)

Define a random error.
A random error causes unpredictable fluctuations in readings due to uncontrollable factors, such as changing environmental conditions.
Define a systematic error.
A systematic error arises from faulty instruments or a flawed method, is repeated in every reading, and affects the accuracy of results.
How can random errors be reduced?
Repeat the measurements several times and calculate a mean average.
How can systematic errors be reduced?
Recalibrate the instrument, or correct or adjust the technique being used.
Define a zero error.
A zero error is a systematic error in which an instrument gives a non-zero reading when the true reading should be zero.
Distinguish between precision and accuracy.
- Precision: how close repeated measurements are to each other
- Accuracy: how close a measurement is to the true value
Random errors affect the .......... of measurements, causing a wider spread of results about the mean.
Random errors affect the precision of measurements, causing a wider spread of results about the mean.
True or False?
Repeating a measurement and averaging reduces systematic error.
False.
Repeating and averaging reduces random error. Systematic error is reduced by recalibrating the instrument or correcting the method.
Define uncertainty.
Uncertainty is the range of values around a measurement within which the true value is expected to lie; it is an estimate.
State the three ways in which uncertainty can be represented.
- Absolute uncertainty — a fixed quantity
- Fractional uncertainty — a fraction of the measurement
- Percentage uncertainty — a percentage of the measurement
How is percentage uncertainty calculated?
$percentage uncertainty = \frac{absolute uncertainty}{measured value} \times 100 %$
What is the uncertainty in a single reading (e.g. from a voltmeter), and in a measurement (e.g. from a ruler)?
- Reading: ± half the smallest division
- Measurement: at least ± one smallest division
How is the uncertainty in repeated data found?
Half the range:
$uncertainty = \pm \frac{1}{2} (largest - smallest value)$
How do you combine uncertainties when adding or subtracting quantities, and when multiplying or dividing them?
- Adding or subtracting: add the absolute uncertainties
- Multiplying or dividing: add the percentage uncertainties
When a measurement is raised to a power, you .......... its percentage uncertainty by that power.
When a measurement is raised to a power, you multiply its percentage uncertainty by that power.
True or False?
An uncertainty and an error are the same thing.
False.
An error is a difference from the true value caused by the equipment or method; an uncertainty is the estimated range within which the true value is expected to lie.

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