Practical Flashcards
(31 cards)
Which experiment is longer? Experiment 1 or 2
Ex1 is longer.
If start with ex2, finish early and spend time on preparing for ex1
When can i ask extra time?
When electrical component is faulty
Analog uncertainty (with pointer)
Half of smallest division
Meter, protractor accuracy (no pointer)
Smallest division
Time uncertainty
1 dp
Repeat measurements for….
Certain: time of oscillations (at least 2 reps)
Likely needed too: Potential difference, micrometre gauge, protractor
s^-1 is measured or calculated?
Calculated; follows sf of s
Calculated sf is…
Follows measured OR add 1 more sf
What’s wrong with this angle data
30.0°
25.5°
No pointer needle. Smallest division is 1° and not half of it
Scales of axis
Multiples of 1:2:5
How to comment if your constant value supports a suggested relationship?
Percentage difference is more/less than 20% (default, subject to change), it does not support/support….
Sources of error relating to:
Oscillations or T
Too few oscillations → use longer rod/greater mass
Difficult to judge a complete oscillation → record video with scale behind, watch frame by frame
Oscillations is not on a vertical plane (NOT APPLICABLE TO CERTAIN SET UP), → use guide (cylinder or square)
REJECT force applied if there’s a lot of repetition.
Sources of error relating to:
Electric circuits
Meter fluctuate → clean contact with wire wool or solder the connections
General source of errors relating to data types
Examples: length like h1-h2
Small value, uncertainty large.
Two measurements are too close.
Dont use your own apparatus
Okay
Read offs from graph is accurate to..
Half the small square
Calculate percentage uncertainty of a meter rule if you measured something of the length 20cm
0.2 OR MORE /20 ×100%
More if more uncertain like pendulum… safe range is 0.5-1.0
OR half the range if repeated measurement (preferred)
REJECT 0.1/20
Difficulty related to hanging things on rods or strips
Wire/string moves on rod during oscillation OR difficult to position in the middle of the rod
Sol; make grooves in the rod
Source of error when Need to move something to a certain degree but the protractor not provided
use clamped protractor so that consistent
Error when needing to place slotted mass on a strips pver certain distances
Difficulty finding centre of mass/ parallex error.
Measure diameter of mass. Instead of measuring to the centre, add half the diameter, then measure to the edge of mass
Error when something has to be set up vertically
May not be vertical
Use set square
Putty is used in an experiment involving mass. What’s the error
Mass of putty is not taken into consideration
MEASURE mass of putty and Add mass of putty to the mass of slotted mass / use adhesive tape
In experiment 2, there’s L0, w0, and t. However, only L, and w are measure multiple times, even though t also changes. What error ?
Change in t is not taken into consideration.
Measure t when stretched (or when whatever changes are made)
Values related to rubber bands is to be measured when straight, but not stretch. What’s the difficulty?
Difficulty determining whether the rubber bands is just straight and not stretched.
Use a Newton meter to hang them
