click below

click below

Normal Size Small Size show me how

# physics aqa

Question | Answer |
---|---|

evidence | data which has been shown to be valid |

accuracy | a measurement result is considered accurate if it is judged to be close to the true value |

calibration | marking a scale on a measuring instrument. For example, placing a thermometer in melting ice to see whether it reads zero, in order to check if it has been calibrated correctly |

Data | Information, either qualitative or quantitative, that has been collected |

measurement error | the difference between a measured value and the true value |

anomalies | these are values in a set of results which are judged not to be part of the variation caused by random uncertainty |

random error | due to results varying in an unpredictable way from one measurement to the next. random errors present when any measurement is made, and cannot be corrected. The effect of random errors can be reduced by making more measurements and calculating a new mean |

systematic error | these cause readings to differ from the true value by a consistent amount each time a measurement is made. they cannot be dealt with by simple repeats, if one is detected must be repeated using a dif technique or set of equipment |

zero error | any indication that a measuring system gives a false reading when the true value of a measurement quantity is zero, a zero error may result in a systematic uncertainty |

fair test | a fair test is one in which only the independent variable has been allowed to affect the dependent variable |

hypothesis | a proposal intended to explain certain facts or observations |

interval | the quantity between readings, e.g a set of 11 readings equally spaced over a distance of 1 meter would give an interval of 10 cm |

precision | precise measurements are ones in which there is very little spread about the mean value. Precision depends only on the extent of random errors - it gives no indication of how close results are to the true value |

prediction | a prediction is a statement suggesting what will happen in the future, based on observation, experience or a hypothesis |

range | the maximum and minimum values of the independent variable or dependent variables; important in ensuring that any pattern is detected |

repeatable | a measurement is repeatable if the original experimenter repeats the investigation using the same method and equipment and obtains the same results |

reproducible | a measurement is reproducible if the investigation is repeated by another person, or by using dif equipment or techniques, and the same results are obtained |

resolution | this is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading |

sketch graph | a line graph, not necessarily on a grid, that shows the general shape of the relationship between two variables |

true value | the value that would be obtained in an ideal measurement |

uncertainty | the interval within which the true value can be expected to lie, with a given level of confidence or probability, e.g the temp is 20 +2, at a level of confidence of 95% |

validity | suitability of the investigative procedure to answer the question being asked |

Valid conclusion | A conclusion supported by valid data, obtained from an appropriate experimental design and based on sound reasoning |

variables | these are physical, chemical or biological quantities or characteristics |

categoric | categoric variables have values that are labels, e.g name of plants or types of material |

continuous | continuous variables can have values (called a quantity) that can be given a magnitude either by counting (as in the case of the number of shrimp) or by measurement (e.g light intensity, flow rate etc) |

control | a control variable is one which may, in addition to the independent variable, affect the outcome of the investigation and therefore has to be kept constant or at least monitored |

dependent | the dependent variable is the variable of which the value is measured for each and every change in the independent variable |

independent | the independent variable is the variable for which values are changed or selected by the investigator |