Alternative to Practical Flashcards
How to produce more accurate or reliable results
- Repeat the experiment to calculate average reading
- Avoid parallax error, look perpendicular to the ruler
- Check for zero error
How to draw an image created from lens
- Inverted from the original object
2. Sides are multiplied by the magnification
How to improve accuracy for a centre of mass experiment
View the string directly in front of the card (lamina)
How to minimise heating effect of a current
- Lower current
- Increase voltage
- Add a lamp
- Increase resistance of a resistor
How to increase accuracy of ray diagrams
- View the base of pins since pins may not be vertical/may be bent
- Keep pins further apart and use more pins
- Avoid parallax error
- Repeat and take average
Improvements to heating, cooling and insulation experiments
- Same initial temperature
- Same volume of water
- Same shape and type of beaker
- Same room temperature
- Stir the water in the beakers
- Record max temperature
How to reduce heat loss
- Insulate the beaker
- Cover beaker with a lid
- Place the beaker in a styrofoam container
How to check if a rule is vertical
- Use a 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 must be of the same height on bench
- Take more readings
- Avoid parallax error in measurement, and look perpendicular to the ruler
- Object, lens and screen are 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
How to improve the method of calculating circumference by string
- Avoid parallax error
- Repeat and take average
- Use thinner string
- Parallel windings of string
Precautions for circuit readings of I and V
For I: limit current so that the temperature doesn’t increase
For I and V: switch off between readings
How to have fair test for pendulum experiments
- Length of pendulum
- Shape of bob
- Number of swings
- Amplitude
Precautions & procedures for electrical experiments
- Check for zero error
- Check that connections are clean
- Switch off current when not making a measurement
- Use low currents/voltages when measuring resistance to avoid heating and changing the resistance you are measuring
Why would the angle of incidence NOT equal the angle of reflection in ray experiments?
- Thickness of pins
- Thickness of mirror
- Protractor not precise
Inaccuracy of ray box method
Thickness of rays
Inaccuracy of pin method
- Pins not straight (bent)
- Pins are too close
- Thickness of lines drawn
Why do we measure 10 oscillations rather than 1?
- To reduce human error
- To give a more accurate value of time taken
- To give an an average time taken
Safety precautions for electrical experiments
- Live wires should not be touched
- Hot objects should not be touched with bare hands, use gloves
- Circuit connections should be checked and approved by the teacher
- Circuit power should be switched off when changing components so that no one experiences electric shocks
Precautions - pendulum, Hooke’s law, trolley, centre of mass
Pendulum: use a small angle for regular oscillations, make sure the bob does not hit anything
Hooke’s law: make sure the elastic limit is not reached (do not overload the spring)
Trolley: make sure the trolley does not knock anything on its way, travels in a straight line
Centre of mass: wait for the card to stop swinging before taking measurement
