Improving Accuracies:
To produce more accurate/reliable results:
- Repeat experiment to calculate the average reading
- Avoid parallax error, look perpendicular to the ruler
- If accuracy in measurement was asked, check for zero error.
Center of mass (with lamina)
- View the string directly in front of the card.
Minimize the heating effect of a current:
- Lower current
- Increase voltage
- Add a lamp
- Increase resistance of a resistor
- Turn off the circuit between readings.
Heating and cooling effects and insulation:
- Same intitil temperature
- The same volume of water
- Same shape and type of beaker
- Same room temperature
- Stirring the water in the beakers
- Record maximum temperature
Heat loss could be reduced by:
- Insulation of beaker
- Covering beaker with a lid
The ruler is vertical:
- Use of set square or protractor
- Plumb line
- Spirit level
Variables in experiments about springs and stretching effect:
- Number of coils
- Length of spring
- Diameter od the spring/wire
- Selection of loads
Improvement made to calculating circumference by sting method:
- Avoid parallax error
- Repeat and average
- Thinner thring
- Parallel winding of string
Readings of voltage and current
- Limit current so that temperature doesn’t increase
@IBResourceDump
- Use a tapping meter
- Switch off between readings
Fari test for pendulum experiments:
- Length of pendulum
- Shape bob
- Number of swings
- Amplitude
Electrical experiments:
- Check for zero error
- Tap the meter to avoid sticking
- Check polarities before closing the switch
- 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 of the resistance you are measuring.
The Cooling Rate of Water:
Apparatus:
- Heater
- Thermometer
- Beaker
- Stopwatch
- Beaker containing water
Procedure:
- Place heater into a beaker and turn it on to raise the temperature of water to 60
degrees celsius.
- Stir the contents of the water and place the thermometer into the beaker.
- Record the starting temperature of the water in the beaker
- Turn on the stopwatch
- Record the readings of the thermometer and stopwatch at regular intervals
- Draw a table and plot a graph to conclude your experiment
Specific Heat Capacity:
Apparatus:
- Solid block
- Drill
- Thermometer
- Heater (known power)
- Cotton wool
@IBResourceDump
Procedure:
- Drill two holes in the block
- Measure the mass of the block
- Place the heater in one lock and the thermometer in the other
- Use cotton wool to properly insulate
- Record the initial temperature of the block
- Tuen on the heater for “x” seconds
- Calculate energy supplied by heater using the formula Q=Pt (Energy =
power*time)
- Note the final temperature of the block
- SHC = Q/mass*change in temperature.
Better Insulators:
Apparatus:
- Two large cans
- Two small cans
- Cotton wool
- Polystyrene beads
- Boiling water
- Thermometers
- Stopwatch
Procedure:
- Put the small cans into the large cans and insulate the small can with cotton wool
and the other with polystyrene beads.
- Pour boiling water into the small cans place the thermometer in them
- Start the stopwatch and take the reading of the temperature at regular intervals
- Record the readings in a table for each thermometer
- The small can that has a higher temperature over the fixed period is better
insulated
- Therefore, the object that provides a less temperature loss over the period id=s
he better insulator.
Resistance and Temperature:
Apparatus:
- Resistor
- Battery
- Connecting wires
- Ammeter
- Voltmeter
- Oven
@IBResourceDump
Procedure:
- Make a circuit with the battery, connecting wires, ammeter, voltmeter and
resistor.
- Measure the resistance of the resistor using the formula R=V/I (Resistance =
voltage/current)
- Heat the resistor int the oven.
- Place the resistor back into the circuit.
- Measure the readings again using the formula R=V/I (Resistance =
voltage/current)
- Draw up a conclusion about how the resistance increases as temperature
increases.
Speed of Sound:
Apparatus:
- Two observers
- Gun
- Stopwatch
Procedure:
- Two observers are set apart at a known distance
- One observer has the gun, the other has the stopwatch
- Observer A fires the gun, observer B starts the stopwatch when he sees the puff
of the smoke
- Observer b stops the stopwatch when he hears the sound and records the time
- Speed = distance/time is used to find the speed
- The observers swap places and the experiment is repeated.
- The values are averaged and the speed of sound is obtained.
Center of Mass:
Apparatus:
- Plane lamina
- Drill
- Thread
- Plumb line
Procedure:
- Make a hole in the lamina
- Hang it so it can swing freely
- Hang a plumb line in the hole and mark the line it passes through
- Repeat the procedure again to get another line
- Intersection if the centre of mass
Stability of simple objects:
@IBResourceDump
- The position of the centre of mass affects the stability of an object
- If the centre of mass is low, it is less likely to tip if tilted
Increase Stability:
- Increase surface area
- Make the object shorter
@IBResourceDump
