Phys - Practical Flashcards
a
Uncertainty of Measurements
Resolution of instruments
Given
Maximum - minimum / 2
Resolution of Calipers
0.01mm
Significant Figures In Table
Same across individual columns
If operations performed with two measurements, use smaller sig fig for result
1 or 2 sig figs for uncertainties
Resolutions & units in headings
Checking That Graph Agrees WIth Equation
- Linear relationship between y & x
- Regression line passes through all data points / error bars
- For min/max, min & max regression lines straddle / don’t origin
For regression, regression line passes / doesn’t origin
Why Does The Theoretical Result Not Align With The Practical Result?
There is something not considered / taken into account in the theoretical equation; mass of spring, dissapative forces etc
Ways In Which You Could Improve The Experiment?
Increase range of independent variable
Increase number of independent variable values tested witin the existing range of values
If not done already, repeat readings to find anomalies and mean
Use instruments with a smaller resolution
Check for reproducibility with other students
Effect of Parallel And Series Springs
In parallel,
k = k1 + k2
In series,
k = 1/(1/k1 + 1/k2)
Circuit of Varying P.D
Use a D.C cell and a varying resistor (rectangle with arrow from bottom left to top right)
Plan Steps
Describe the method of the experiment; Mention:
- instruments used
- independent (how many values you will test), dependent and control variables
- how you will plot the graph and find m and c
- trial readings
- repeat readings
- accounting for zero error and parallax error (if appropriate)
- logarithmic equation (if appropriate)
Equation Match
Look out for powers, units
Include table units in graph, but convert when calculating gradient
Graph If Equation Has No Intercept (and later 3 mark for interpreting the graph)
Both x and y start on 0
Use Data
Specifically use values to support your explanation.
If you can, use numerical descriptions (d will decrease by factor of x)
Gradient Units
DON’T convert to SI units when calculating gradient
DO convert when using gradient for calculations
Percentage Uncertainties
% = (change x / x) x 100 x power of value (even fractional)
Ways To Reduce Uncertainty?
Use instrument with smaller resolution
Use larger values
Calibrate equipment
