Practical Skills In Physics Flashcards
Accuracy Definition
The degree to which a value obtained by experiment is close to the actual value or true value.
Precision Definition
The degree to which repeated values, collected under the same experimental conditions, show the same results.
What is a Systematic Error
This is an error inherent in the experiment or due to human error.
Will you always know you have a Systematic Error, and how can you go about fixing it
Sometimes, you might not even know you have a systematic error.
They have to be identified and put right, or your “precise” measurements will cluster round a wrong value!
- Its important to estimate the size of your systematic error and subtract it from the rest of the results
- At the very least, you must write about it.
Example of a Systematic error
Examples:
- A shrunken ruler
- A clock running fast or slow
What is a zero error? (+example)
A zero error is when a measuring system gives a false reading when the true value of a measured quantity is zero.
Example:
- The needle on an ammeter failing to return to zero when no current flows
What is a Parallax Error
A parallax error is when you view something at an angle, rather than head-on, which gives the impressions of a different value.
Example: Viewing a measuring cylinder from anything other than eye-level
How Anomalous Results occur
.
What is the best way to spot Anomalous Results
.
What do Error Bars do
Error bars should reflect the uncertainty around each point on the graph
Equation to find Percentage Uncertainty
Percentage Uncertainty = (Uncertainty / Average Value) x 100
or
Percentage Uncertainty = (Finest Division / Reading Taken) x 100
Example Question:
Calculate the Percentage Uncertainty when the:
- Reading on the meter = 12.6 V
- Finest division = 0.2 V
Percentage Uncertainty = (Finest Division / Reading Taken) x 100
% Uncertainty = (0.2/12.6) x 100 = 1.6%
