Improving Accuracy

• To produce more accurate or reliable results:

  • Repeat the experiment to calculate the average reading.
  • To avoid parallax error, look perpendicular to the ruler.
  • If measurement accuracy was asked, check for zero error.
• To draw an image created from the lens:

  • Inverted from the original object.
  • Sides are multiplied by the magnification.
• Centre of mass experiment (with the lamina):

  • You view the string directly in front of the card.
• Minimizing the heating effect of a current:

  • Do not add any electrical components
  • Decrease voltage
  • Decrease the resistance of a resistor
• To increase the accuracy of ray diagrams:

  • View bases of pins since pins may not be vertical
  • Keep pins further apart and use more pins
  • Avoid parallax; explain action and reason
  • Repeats and average
• Improvements made to experiments about heating/cooling effects and insulation

  • Same initial temperature.
  • The same volume of water.
  • Same shape and type of beaker.
  • It's the same room temperature.
  • Stirring the water in the beakers.
  • Record max. temperature
• Heat loss could be reduced by:

  • Insulation of beaker.
  • Cover the beaker with a lid.
• How to check if a rule is vertical:

  • Use of set square or protractor
  • Plumb line
  • Spirit Level
• Precautions taken in experiments about the formation of images by a lens

  • Use a darkened area
  • Object and lens are the same height on the bench
  • Take more readings
  • Avoid parallax errors in measurement and look perpendicular to the ruler.
  • Object/lens/screen perpendicular to the bench
• Variables in experiments about springs and stretching effect:

  • Number of coils
  • Length of spring
  • Diameter\thickness of spring or wire
  • Selection of loads
• Improvement made to calculating circumference by string method

  • Avoid parallax error
  • Repeats and average
  • Thinner string
  • Parallel winding of springs
• Precautions for circuit readings of I and V so that they are accurate:

  • For I specifically:
  • Limit current so that temp. doesn't increase
  • Use a tapping meter
  • For I and V: Switch off between readings.
• Fair test for pendulum experiments:

  • Length of pendulum
  • Shape of bob
  • No. of swings
  • Amplitude
• Precautions and procedures in electrical experiments:

  • Check for a zero error
  • Tap the meter to avoid sticking
  • Initially, choose the highest range for the ammeter/voltmeter, then reduce the range for the ammeter so that the deflection is almost full-scale
  • Always check polarities before closing the switch (completing the circuit)
  • Always check that connections are clean.
  • Switch off the current when not making a measurement.
  • When measuring resistance, use low currents/voltages to avoid heating and changing the resistance you are measuring.