# Exam Help

P2

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## Errors

Systematic error

- Error with your method which affects all results

Random error

- When you repeat results in different conditions

Zero error

- When e.g. voltmeter does not read zero when you begin affected all results by the same degree

Pelimenary test

- Where you do your experiment before hand to identify control variables, intervels and range

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- Allows you to calculate a more reliable mean average

- Allows you to identify any annomalies

- Reduces risk of random errors

Anomolous results

- Don't fit the trend

Accuracy

-Close to the true value so 10, 11, 12 are more accurate than 10,13,18

Precision

- Smaller scale divisions so 0.01 is more presise than 0.1

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Calibration

- Comparing something to a known value

Why are data loggers better than humans measuring

- As with a data logger the conditions remain constant but with humans they can vary

- Humans get tired

- Humans can only get very few readings whereas data loggers can take multiple readings resulting in a more reliable mean average

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- Connect a Geiger-Muller tube to  counter and if it shows a value there is radiation. It will most likely show a value to due bakcground radiation

Forces in the same direction add up, forces in the opposite direction takeaway (forces can not be negative don't get mixed up with momentum and resulatnt forces)

Data questions the answers are most likely in the text

Read unit and convert correctly 0.1g = 0.1/1000 = 0.0001kg

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Cirect current is the flow of current in one direction only

Alternating current is constantly changing direction it goes in one direction and then the opposite direction 500 times a second.

k.e= 0.5 x mass x velocity squared (do not forget to square)

RCCB is better than a fuse as it can be reset and disconects a lot faster.

Travelling uphil requires more power.

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Gain = controls voltage axis

Timebase = controls time axis

Electricity takes the path of least resistance always.

Series circuit when components are connected all in one loop

Paralell there is more than one path for current to take

momentum is not always conserved is external forces are acting.

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