General principles physics

• What is required to confirm or challenge a theory in experiments?

  Experiments are required.
• What must an experimental result be for it to be accepted?

  The experiment must be repeatable, reproducible, and accurate.
• What does it mean for an experiment to be repeatable?

  Consistent results are obtained when the experiment is repeated by the experimenter.
• What does it mean for an experiment to be reproducible?

  Other experimenters obtain similar results possibly using different methods.
• What does accuracy refer to in an experiment?

  Obtaining a value that is close to the true value.
• What is an example of a measuring device mentioned?

  Analogue voltmeter.
• How does the choice of terminal affect a voltmeter's sensitivity?

  The choice will alter the sensitivity of the meter.
• What happens when voltmeter B is more sensitive than voltmeter A?

  Voltmeter B shows a potential difference (pd) of 1V while voltmeter A shows a pd of 4V.
• What is instrument resolution?

  The smallest non-zero value of the measured quantity that can be shown on the device.
• How should values for readings or measurements be quoted?

  To the number of significant figures consistent with the resolution of the measuring device.
• What is the resolution of a voltmeter that measures a pd of 4V?

  0.5V.
• How many judgements are involved in a reading taken from a measuring device?

  A single judgement by the experimenter.
• How many judgements are involved in a measurement made using a measuring device?

  Two judgements by the experimenter.
• What is an example of a device that requires only one judgement?

  Thermometer.
• What is an example of a device that requires two judgements?

  Ruler.
• What does uncertainty measure in an experiment?

  The spread of values for a reading or measurement likely to contain the true value.
• How is uncertainty expressed in a measurement?

  As absolute uncertainty or percentage uncertainty.
• What is the absolute uncertainty in the measurement of 0.51 m with an uncertainty of ±0.02 m?

  I = 0.51 ± 0.02 m.
• How is percentage uncertainty calculated?

  By dividing the absolute uncertainty by the measured value and multiplying by 100.
• What should good experimental designs aim to do regarding uncertainty?

  Reduce the uncertainty in the outcome of an experiment.
• What factors should be considered when assessing uncertainty?

  The resolution of the instrument, manufacturer's tolerance, experimenter's judgements, and adopted procedures.
• How is the minimum uncertainty in a reading or measurement stated?

  As absolute uncertainty or percentage uncertainty.
• What is the absolute uncertainty for a temperature reading of 24.5°C using a thermometer with a resolution of 0.5°C?

  ΔT = ±0.25 °C.
• How should the percentage uncertainty be expressed for a temperature reading of 24.5°C with an absolute uncertainty of ±0.3°C?

  T = 24.5°C ± 1%.
• What is the absolute uncertainty for a reading of 24°C using a thermometer with a resolution of 1°C?

  ±0.5°C.
• How is the uncertainty in a length measured on a ruler with 1 mm resolution expressed?

  As ±0.5 mm.
• What is the percentage uncertainty for a length of 11.4 cm measured with a ruler with 1 mm resolution?

  0.9%.
• How does the positioning of the pencil on the ruler affect uncertainty?

  It contributes to the uncertainty in the measurement.
• What is the resolution of a stopwatch?

  Hundredths of a second.
• What should be recorded in the results table when using a stopwatch?

  The full reading on the stopwatch.
• How does the uncertainty in measuring the length of a piece of wire compare to the resolution of the ruler?

  The uncertainty could be higher than the ±1 mm uncertainty due to the resolution.
• What is the absolute uncertainty in the mass of a block measured as 36.2 g with a resolution of ±0.1 g?

  ±0.1 g.
• How is the percentage uncertainty in mass calculated for a block measured at 36.2 g?

  As (0.1/36.2) × 100 = 3%.
• What should be done to reduce parallax error when measuring?

  Position the pencil directly above the scale.
• What is the mean current if three readings of 1.22 A, 1.24 A, and 1.18 A are taken?

  1. 21 A.
• How is the absolute uncertainty in a mean calculated?

  It is the uncertainty of the individual measurements combined.
• What happens to the uncertainty when two measurements of the same nature are added or subtracted?

  The uncertainty of the result is the sum of the two separate uncertainties.
• What is the rule for combining uncertainties when a quantity is raised to a power?

  The percentage uncertainty of the result is the uncertainty of the quantity multiplied by the power.
• What is the purpose of experiments in science?

  Experiments are required to confirm a theory or challenge an established theory.
• What are the three key criteria for an experimental result to be accepted?

  For an experimental result to be accepted, the experiment must be repeatable, reproducible and accurate.