CAIE IGCSE PHYSICS SUMMARIZED NOTES ON THE ALTERNATIVE TO PRACTICAL SYLLABUS Prepared for Qudsia Atiq for personal use only. CAIE IGCSE PHYSICS
Apparatus: Two large cans, two small cans, cotton wool,
polystyrene beads, boiling water, thermometers, 1. Safety Precautions stopwatch Procedure: Live wires should not be touched. Put the small cans into the large cans and insulate the Hot objects should not be touched with bare hands - small can with (i) cotton wool and (ii) polystyrene gloves should be used beads Circuit connections should be checked and approved by Pour boiling water into the small cans and place the the teacher and then only the circuit should be switched thermometers in them. on Start the stopwatch and take readings of temperature While changing components of the circuit the power at regular intervals. should be switched off so that one should not experience Record readings in a table for each insulator. electric shocks. The small can that has the higher temperature over Safety goggles, gloves and other safety components the fixed period is better insulated. should be used while handling experiments. Hence, object that provides a less temperature loss While handling a mercury thermometer one should take over the period is the better insulator. care of the mercury spills.
5. Refraction of Light 2. Specific Heat Capacity Apparatus: Ray Box, Rectangular piece of glass, Plain Apparatus: Solid block, Drill, Thermometer, Heater (of paper, Pencil. known power), Cotton wool. Procedure: Procedure: Place the Plain paper below the rectangular piece of Drill two holes in the block. glass. Measure the mass of the block. Project a ray towards the glass. Place the heater in one of the holes, the thermometer Make two points to mark the incident ray, two to mark in the other. the refracted ray and two to mark the emergent ray. Use cotton wool to properly insulate/lag the block. Join all the lines, measure the angles and calculate Note the initial temperature of block and turn on refractive index. heater for x seconds Repeat with different angles; Snell's law shown. Calculate Heat Energy Supplied by heater using formula Q=Pt. Note the final temperature of block. 6. Resistance and Q Specific heat capacity = m×Δt .
Temperature 3. Cooling Rate of Water Apparatus: Resistor, Battery, Connecting wires, Ammeter, Voltmeter, Oven. Apparatus: Heater, Thermometer, Beaker, Stopwatch, Procedure: Beaker containing Water. Make a circuit with the battery, connecting wires, Procedure: ammeter and voltmeter, resistor. Place heater into beaker and turn it on to raise the Measure the resistance of the resistor using the temperature of water to 60°C formula R=V/I. Stir the contents of the water and place thermometer Heat the resistor in the oven. Place the resistor back into the beaker. into the circuit. Note the starting temperature and turn on the Measure the readings again and calculate R=V/I. stopwatch. Draw up a conclusion about how the resistance Take readings of the thermometer and stopwatch at increases as temperature increases. regular intervals (e.g. 60 sec). Draw up a table and plot a graph to conclude your experiment. 7. Speed of Sound Apparatus: Two observers, Gun, Stopwatch. 4. Picking a Better Insulator 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 Record max. temperature stopwatch when he sees the puff of smoke. Heat loss could be reduced by: Observer B stops the stopwatch when he hears the Insulation of beaker. sound and the time is noted. Cover the beaker with a lid. Speed = Distance Time applied. How to check if a rule is vertical: The observers swap positions and repeat the Use of set square or protractor experiment. Plumb line The values are averaged and the speed of sound is Spirit Level obtained. Precautions taken in experiments about the formation of images by a lens Use a darkened area 8. Centre of Mass Object and lens are the same height on the bench Take more readings Centre of mass of a plane lamina: Avoid parallax errors in measurement and look Make a hole in the lamina. perpendicular to the ruler. Hang it so it can swing freely. Object/lens/screen perpendicular to the bench Hang a plumb line in the hole and mark the line it Variables in experiments about springs and stretching passes through. effect: Repeat the procedure again to get another line Number of coils Their intersection point is the center of mass. Length of spring Stability of simple objects: Diameter\thickness of spring or wire The position of the center of mass affects an object’s Selection of loads stability. If the center of mass of an object is low, it is Improvement made to calculating circumference by string less likely to tip if tilted. method To increase stability: (i) Increase surface area (ii) widen Avoid parallax error the base of the object. Repeats and average Thinner string Parallel winding of springs 9. Improving Accuracy Precautions for circuit readings of I and V so that they are accurate: To produce more accurate or reliable results: For I specifically: Repeat the experiment to calculate the average Limit current so that temp. doesn't increase reading. Use a tapping meter To avoid parallax error, look perpendicular to the For I and V: Switch off between readings. ruler. Fair test for pendulum experiments: If measurement accuracy was asked, check for zero Length of pendulum error. Shape of bob To draw an image created from the lens: No. of swings Inverted from the original object. Amplitude Sides are multiplied by the magnification. Precautions and procedures in electrical experiments: Centre of mass experiment (with the lamina): Check for a zero error You view the string directly in front of the card. Tap the meter to avoid sticking Minimizing the heating effect of a current: Initially, choose the highest range for the Do not add any electrical components ammeter/voltmeter, then reduce the range for the Decrease voltage ammeter so that the deflection is almost full-scale Decrease the resistance of a resistor Always check polarities before closing the switch To increase the accuracy of ray diagrams: (completing the circuit) View bases of pins since pins may not be vertical Always check that connections are clean. Keep pins further apart and use more pins Switch off the current when not making a Avoid parallax; explain action and reason measurement. Repeats and average When measuring resistance, use low Improvements made to experiments about currents/voltages to avoid heating and changing the heating/cooling effects and insulation resistance you are measuring. Same initial temperature. The same volume of water. Same shape and type of beaker. 10. Inaccuracies It's the same room temperature. Stirring the water in the beakers. Why angle i is NOT equal to angle r in ray experiment:
Thickness of mirror Label axis Protractor is not precise Choose a proper scale Inaccuracy of ray box method: thickness of rays. Well-judged best fit line Inaccuracy of pin method: pins not straight, or too close, Thin and neat lines or thickness of lines drawn. Measuring the gradient: Measuring 10 oscillations rather than 1: Draw a triangle on graph Reduce human errors Use clear lines Give more accurate value of time taken (T) Triangle must be larger than half the line Gives an average of T For 2 values to be directly proportional, graph of the values be a straight line from origin.
