Practical Skills Flashcards
What is resolution of a measuring device?
The smallest division on the scale
In experiments what is precision?
A measure of the spread of the values about a mean value
(high precision = small spread)
Random errors determine precision of data
How is precision different to accuracy?
Precision is how close the values are to a mean value
Accuracy is how close that mean value is to the actual value
Results can be precise but inaccurate (eg with a systematic error)
What makes a measurement accurate?
If it is close to the true value (within its absolute uncertainty)
What is a measurement error?
Taking a reading and that is different to the actual value
(caused by random or systematic errors)
What are the 2 types of measurement errors?
**1. Random
2. Systematic **
Subcategories: zero, callibration, parallax, reaction time
What is an anomaly?
An incorrect measurement outside of the range of uncertainty
How do you deal with anomalies in results?
- Repeat measurement if possible
- If not discount anomalous result
What is a random error?
Something that causes results to be randomly spread out around a true value (eg repeat measurements for freefall)
How do you reduce random errors in experiments?
Take repeat measurements and calculate averages
What is a systematic error?
An error that causes all results to be affected by the same amount (eg reaction time using stopwatch)
Can be caused by miscalibrated equipment (zero error)
How do you reduce systematic errors in experiments?
Ensure equipment is correctly calibrated
What is a parallax error?
The viewing angle affects the measurement
What 2 things do you do to reduce parallax errors in experiments?
- Bring eyeline as level with scale as possible
- Place measuring equipment as close to object as possible
What type of error is this?
Random error (Reduced taking repeats and average)
What type of error is this?
Parallax
What type of error is this?
Systematic
What kind of error is this?
Systematic
What makes an experiment a fair test?
Only one variable is changed (independent variable) to affect the dependent variable
For a scientific result to be accepted what 2 conditions must the experiment meet?
- Repeatable - If you can perform the experiment again and get the same result
- Reproducible - If someone else can perform the same experiment and get the same result
In experimental science what is absolute uncertainty?
The interval which the actual value of a measurement is expected to lie in
What is the absolute uncertainty here?
±0.01V
How is absolute uncertainty for a measurement determined?
- = resolution of equipment
or - Half range of repeats (discount anomalies)