Physics Paper 1 - Required practicals

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an amount of water or any other way of heating something. What's the resolution of temperature measurements? This experiment could be repeated and you'd get slightly different readings. They could ask about repeatability and ask you to calculate the mean or the uncertainty. GCSE Required Practical - Physics 1 - Investigating Resistance Resistance: how difficult it is for current to flow through part of the circuit. Example Apparatus What's the point of the practical? To find out resistance of a wire. (You could look at different lengths of wire, different thicknesses, or even different temperatures) Results: resistance (W) = potential difference (V) current (A) The longer the wire, the more resistance The thicker the wire, the less resistance The higher the temperature the more resistance Voltmeter: measures the potential Difference Ammeter: measures the current voltmeter power pack ammeter ■ wire Metre stick: Measures the length of wire that the current is going through What may they ask us about? - Why must the power pack be kept on a low potential difference / What are the hazards (The wire will get very hot, could burn you) - Explain how the temperature affects the resistance (as the wire gets hot, the ions inside the wire vibrate faster so there are more collisions with the electrons cannot flow as easily) - Why is it important to switch the electricity off in between each reading (to let the wire cool down, as temperature affects resistance) - What sort of error could cause all the ammeter/voltmeter readings to be too high (a zero error - the meters need to be set at zero to start with) - Resolution of measurements, repeatability, reproducibility, control variables etc etc GCSE Required Practical - Physics 1 - Investigating Electrical Components (lamp, diode, resistor) diode: only allows current to flow one way Component: part of a circuit Current: the flow of charge Potential Difference (V): the energy transferred to part of a circuit by each coulomb of charge Resistor: limits the current in a circuit Example Apparatu What's the point of the practical? To find out how current and potential difference change in different components Results: Current Resistor Current -7= lamp Potential difference Potential difference Current Diode Potential difference Voltmeter: measures the potential Difference Ammeter: measures the current A 3V battery + V resistor Resistor: what we're testing. (can be replaced with a lamp, then a diode What may they ask us about? - Explain the pattern for each component (resistor: fixed resistance - more PD =more current. Lamp: more PD = more current but at high PD, the filament gets hot, ions vibrate so resistance increases and current levels off. Diode: current can only flow in one direction) - Resolution of measurements, repeatability, reproducibility, control variables etc etc GCSE Required Practical - Physics 1 - Resistors in Series and Parallel Resistor: limits the current in a circuit What's the point of the practical? To find out what happens to the total resistance when resistors are put in series and in parallel Results for series circuits the total resistance is the same as both resistors added up. Each time you add a resistor, you get more resistance and less current Example Apparatus 3V R₁ 1V + R₂ 492 Series circuit 9.0V 0.9AY R3 R₁ 3.092 Parallel circuit Results for parallel circuits The total resistance is less than the smallest resistor. Each time you add more resistors, the current increases and the total resistance decreases. (the are more 'routes' overall for the current) What may they ask us about? Why aren't your results completely accurate? (because the meters aren't completely accurate, the power pack potential difference fluctuates slightly, the temperature of the wires changes which affects resistance) What is the resolution of measurements? (e.g. 0.41A, 0.32A, 0.39A are all to 0.01 resolution) They may ask you to calculate resistance, current or PD. Or ask what happens if you add/take away resistors. GCSE Required Practical - Physics 1 - Resistors in Series and Parallel Resistor: limits the current in a circuit What's the point of the practical? To find out what happens to the total resistance when resistors are put in series and in parallel Results for series circuits the total resistance is the same as both resistors added up. Each time you add a resistor, you get more resistance and less current Example Apparatus 3V R₁ 1V + R₂ 492 Series circuit 9.0V 0.9AY R3 R₁ 3.092 Parallel circuit Results for parallel circuits The total resistance is less than the smallest resistor. Each time you add more resistors, the current increases and the total resistance decreases. (the are more 'routes' overall for the current) What may they ask us about? Why aren't your results completely accurate? (because the meters aren't completely accurate, the power pack potential difference fluctuates slightly, the temperature of the wires changes which affects resistance) What is the resolution of measurements? (e.g. 0.41A, 0.32A, 0.39A are all to 0.01 resolution) They may ask you to calculate resistance, current or PD. Or ask what happens if you add/take away resistors. Density: = a substance's mass per unit volume. What's the point of the practical? To find out the density of different materials. Cubes of material are easy for volume (length x width x height). For irregular shapes, you need a eureka can to work out the volume Results Material Aluminium Steel Mass (g) 22.3 GCSE Required Practical - Physics 1 - Calculating Density 50.2 Volume (cm³) 8.0 6.4 Density (g/cm³) 2.79 7.84 Example Apparatus Finding Volume density Eureka can Measuring cylinder = mass m volume V Scout Pro 2.61- Finding Mass 200 What may they ask us about? What is the resolution of the balance? (0.1g in this case) How could you get errors when using the eureka can? (water may spill out of the sides if you drop the object in too quickly /there may already be some water in the measuring cylinder / the water might not be at exactly the level of the spout) How could you get errors when weighing the object (the balance may not be at exactly zero to start with (not calibrated)) What is the uncertainty of the measurements? (the balance has a ±0.05 uncertainty here as it only goes up in 0.1's)