Exampro GCSE Physics. P2 Circuits and Electricity Self Study Questions Higher tier. Name: Class: Author: Date: Time: 90. Marks: PDF

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Exampro GCSE Physics P2 Circuits and Electricity Self Study Questions Higher tier Name: Class: Auth: Date: Time: 90 Marks: 90 Comments: Page of 33 Q. (a) The diagram shows a student touching the metal
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Exampro GCSE Physics P2 Circuits and Electricity Self Study Questions Higher tier Name: Class: Auth: Date: Time: 90 Marks: 90 Comments: Page of 33 Q. (a) The diagram shows a student touching the metal dome of a Van de Graaff generat. When the generat is switched on, the metal dome becomes negatively charged. Explain why the student s hair stands on end when the generat is switched on (b) When the potential difference between the student and a nearby earthed metal dome reached 5 kv, a spark jumped between the student and the earthed dome. The spark transfmed 30 mj of energy into heat, light and sound. ( mj = 0.00 J) Use the equation in the box to calculate the charge carried by the spark. energy transfmed = potential difference charge Charge transferred =... coulombs (c) What name is given to the rate of flow of charge?... () (Total 5 marks) Page 2 of 33 Q2. (a) Figure shows the apparatus used to obtain the data needed to calculate the resistance of a thermist at different temperatures. Figure Power supply (i) In the box below, draw the circuit symbol f a thermist. () Use the data given in Figure to calculate the resistance of the thermist at 20 C. Use the crect equation from the Physics Equations Sheet. Resistance =... ohms Page 3 of 33 (iii) Figure 2 shows the axes f a sketch graph. Complete Figure 2 to show how the resistance of the thermist will change as the temperature of the thermist increases from 20 C to 00 C. Figure 2 Temperature in C () (iv) Which one of the following is most likely to include a thermist? Tick ( ) one box. An automatic circuit to switch a plant watering system on and off. An automatic circuit to switch an outside light on when it gets dark. An automatic circuit to switch a heating system on and off. () (b) The ammeter used in the circuit has a very low resistance. Why is it imptant that ammeters have a very low resistance? () Page 4 of 33 (c) The table below gives the temperature of boiling water using three different temperature scales. Temperature Scale 00 Celsius ( C) 22 Fahrenheit ( F) 80 Réaumur ( Re) Scientists in different countries use the same temperature scale to measure temperature. Suggest one advantage of doing this () (d) A student plans to investigate how the resistance of a light-dependent resist (LDR) changes with light intensity. The student starts with the apparatus shown in Figure 2 but makes three changes to the apparatus. One of the changes the student makes is to replace the thermist with an LDR. Describe what other changes the student should make to the apparatus (Total 9 marks) Page 5 of 33 Q3. The picture shows an electric cooker hob. The simplified circuit diagram shows how the four heating elements connect to the mains electricity supply. The heating elements are identical. When all four heating elements are switched on at full power the hob draws a current of 26 A from the 230 V mains electricity supply. (a) Calculate the resistance of one heating element when the hob is switched on at full power. Use the crect equation from the Physics Equations Sheet. Give your answer to 2 significant figures Resistance =... Ω (3) Page 6 of 33 (b) The table gives the maximum current that can safely pass through copper wires of different cross-sectional area. Cross-sectional area in mm 2 Maximum safe current in amps (i) The power sockets in a home are wired to the mains electricity supply using cables containing 2.5 mm 2 copper wires. Most electrical appliances are connected to the mains electricity supply by plugging them into a standard power socket. It would not be safe to connect the electric cooker hob to the mains electricity supply by plugging it into a standard power socket. Why? Describe the structure of the cable that should be used to connect the electric cooker hob to the mains electricity supply. (3) Page 7 of 33 (c) Mains electricity is an alternating current supply. Batteries supply a direct current. What is the difference between an alternating current and a direct current? (Total 0 marks) Q4. The current potential difference graph f one type of electrical component is drawn below. (a) What is the component?... () (b) Complete the diagram to show a circuit that can be used to obtain the data needed to plot the graph. Use the crect circuit symbol f each component that you add to the diagram. Page 8 of 33 (c) (i) What is the current through the component when the potential difference across the component is 0.8 volts? Current... amps () Use the equation in the box to calculate the resistance of the component when the potential difference across it is 0.8 volts. potential difference = current resistance Show clearly how you wk out your answer. Resistance =... Ω (Total 6 marks) Q5. (a) A student set up the circuit shown in the diagram. The student uses the circuit to obtain the data needed to plot a current - potential difference graph f a diode. (i) Draw, in the boxes, the circuit symbol f a diode and the circuit symbol f a variable resist. Diode Variable resist Page 9 of 33 The student made two mistakes when setting up the circuit. What two mistakes did the student make? (b) After crecting the circuit, the student obtained a set of data and plotted the graph below. Potential difference in volts (i) At what potential difference did the diode start to conduct an electric current?... V () Use data from the graph to calculate the resistance of the diode when the potential difference across the diode is 0.3 V. Use the crect equation from the Physics Equations Sheet. Resistance =... ohms (3) Page 0 of 33 (c) The diagram shows the trace produced by an alternating current (a.c.) supply on an oscilloscope. Each hizontal division on the oscilloscope screen represents a time of 0.0s. (i) Calculate the frequency of the a.c. supply. Frequency =... hertz A diode is now connected in series with the a.c. power supply. Why does the diode cause the trace on the oscilloscope screen to change? (Total 2 marks) Page of 33 Q6. The diagram shows a simple light-sensing circuit. (a) The graph, supplied by the manufacturer, shows how the resistance of the component labelled X varies with light intensity. (i) What is component X? () Use the graph to find the resistance of component X when the light intensity is 20 lux. () Page 2 of 33 (iii) When the light intensity is 20 lux, the current through the circuit is A. Use the equation in the box to calculate the reading on the voltmeter when the light intensity is 20 lux. potential difference = current resistance Show clearly how you wk out your answer. Voltmeter reading =... volts (b) Use the grid below to show how the voltmeter reading in the light-sensing circuit varies with light intensity. (i) Add a suitable scale to the y-axis (vertical axis). Complete the sketch graph by drawing a line on the grid to show how the voltmeter reading will vary with light intensity. () Page 3 of 33 (c) The following passage is taken from the technical data supplied f component X by the manufacturer. F any given light intensity, the resistance of this component can vary by plus minus 50% of the value shown on the graph of light intensity and resistance. (i) Calculate the maximum resistance that component X could have at 20 lux light intensity. Maximum resistance =... kilohms () Explain why this light-sensing circuit would not be used to measure values of light intensity. (Total 0 marks) Q7. A set of lights consists of 20 lamps connected in series to the 230 V mains electricity supply. (a) When the lights are switched on and wking crectly, the current through each lamp is 0.25 A. (i) What is the total current drawn from the mains supply? () Page 4 of 33 Use the equation in the box to calculate the charge passing through one of the lamps in 5 minutes. charge = current time Show clearly how you wk out your answer and give the unit. Total charge =... (3) (b) One of the lamps in the set is a fuse lamp. This contains a filament which melts if a fault occurs. A sht time after the lights are switched on, a fault causes the filament inside the fuse lamp to melt and all the lamps go out. The householder cannot find another fuse lamp so connects a piece of aluminium foil across the contacts inside the fuse lamp holder. When switched on, the nineteen remaining lamps wk. What the householder has done is dangerous. Explain why (Total 6 marks) Page 5 of 33 Q8. The diagram shows the structure of a cable. The cable is part of an undersoil heating circuit inside a large greenhouse. (a) The cable is connected to the mains electricity supply through a residual current circuit breaker (RCCB). If the cable is accidentally cut the RCCB automatically switches the circuit off. (i) What is the frequency of the mains electricity supply in the UK? () What happens, as the cable is cut, to cause the RCCB to switch the circuit off? (iii) A circuit can also be switched off by the action of a fuse. Give one advantage of using a RCCB to switch off a circuit rather than a fuse. () (b) The 230 volt mains electricity supply causes a current of amps to flow through the cable. (i) Calculate the amount of charge that flows through the cable when the cable is switched on f 2 hours and give the unit. Use the crect equation from the Physics Equations Sheet. Charge =... (3) Page 6 of 33 Calculate the energy transferred from the cable to the soil in 2 hours. Use the crect equation from the Physics Equations Sheet. Energy transferred =... J (c) The heating circuit includes a thermist. The thermist is buried in the soil and acts as a thermostat to control the increase in the temperature of the soil. Describe how an increase in the temperature of the soil affects the thermist (Total marks) Q9. (a) Describe the difference between an alternating current (a.c.) and a direct current (d.c.) Page 7 of 33 (b) The diagram shows how the electric supply cable is connected to an electric kettle. The earth wire is connected to the metal case of the kettle. If a fault makes the metal case live, the earth wire and the fuse inside the plug protect anyone using the kettle from an electric shock. Explain how (Total 4 marks) Page 8 of 33 Q0. (a) The picture shows a person using a set of electronic Body Fat Scales. When the person stands on the scales, a small, harmless, electric current passes through the person s body. The scales then calculate the resistance of the person s body and convert the resistance into a prediction of body fat content. (i) The scales contain two 3 V cells joined in series. Calculate the resistance of a person s body, if when he stands on the scales, a current of 0.2 ma passes through his body. 000 ma = A Use the crect equation from the Physics Equations Sheet. Show clearly how you wk out your answer and give the unit. Resistance =... (3) The scales can only produce a prediction of body fat content and not an accurate measurement. Suggest why. () Page 9 of 33 (iii) It is recommended that the scales are not used immediately after a person has drunk a large amount of water. Suggest why. (b) The diagram shows how someone could get an electric shock from accidentally cutting into an electric cable. If this happens, and a Residual Current Circuit Breaker (RCCB) is being used, the circuit will switch off automatically. (i) A faulty appliance circuit can be switched off by a RCCB a fuse. Compare the action of a RCCB with the action of a fuse. The graph shows how the severity of an electric shock depends on the size of the current and the time that the current flows through the body. Page 20 of 33 Using the RCCB helps prevent an electric shock seriously injuring the person using the hedge trimmers. Using infmation from both the diagram and the graph explain how. (Total 0 marks) Page 2 of 33 Q. (a) The resistance of a 24 W, 2 V filament lamp depends on the current flowing through the lamp. F currents up to 0.8 A, the resistance has a constant value of 2.5 Ω. (i) Use the equation in the box to calculate the potential difference across the lamp when a current of 0.8 A flows through the lamp. potential difference = current resistance Show clearly how you wk out your answer. Potential difference =... V When the potential difference across the lamp is 2 V, the current through the lamp is 2 A. On the axes below, draw a current potential difference graph f the filament lamp over the range of potential difference from 0 to 2 volts. (iii) Why does the resistance of the lamp change when the current through the lamp exceeds 0.8 A? () Page 22 of 33 (b) The lamp is now included in a circuit. The circuit is switched on f 2 minutes. During this time, 72 coulombs of charge pass through the lamp. Use the equation in the box to calculate the energy transfmed by the lamp while the circuit is switched on. energy transfmed = potential difference charge Show clearly how you wk out your answer Energy transfmed =... J (Total 7 marks) Page 23 of 33 M. (a) each hair gains the same (type of) charge (each) hair is negatively charged do not accept hair becomes positively charged (each) hair gains electrons similar charges repel accept positive charges repel providing first marking point is in terms of positive charge negative charges repel electrons repel (b) μ C accept crect substitution and transfmation f mark ie 30 / 5.03 / / / 5 answers 2 and gain mark 2 (c) current do not accept amp / amperes [5] M2. (a) (i) 360 allow mark f crect substitution, ie 9 = R 2 Page 24 of 33 (iii) sketch graph of crect shape, ie (iv) An automatic circuit to switch a heating system on and off. (b) so ammeter reduces / affects current as little as possible accept so does not reduce / change the current (it is measuring) accurate reading is insufficient not change the resistance is insufficient (c) gives a common understanding accept is easier to share results accept can compare results do not need to be converted is insufficient prevent errs is insufficient (d) replace Bunsen (and water) with a lamp accept any way of changing light level replace thermometer with light sens accept any way of measuring a change in light level datalogger alone is insufficient [9] M3. (a) 35 an answer with me than 2 sig figs that rounds to 35 gains 2 marks allow 2 marks f crect method, ie allow mark f I = 6.5 (A) R = an answer 8.8 gains 2 marks an answer with me than 2 sig figs that rounds to 8.8 gains mark 3 Page 25 of 33 (b) (i) (maximum) current exceeds maximum safe current f a 2.5 mm 2 wire accept power exceeds maximum safe power f a 2.5 mm 2 wire (maximum) current exceeds 20 (A) (maximum) current = 26 (A) is insufficient a 2.5 mm 2 wire would overheat / melt accept socket f wire do not accept plug f wire (contains) live, neutral and earth wires accept is a three-ce cable cross-sectional area of (live and neutral) wire(s) (minimum of) 4 mm 2 accept 6 mm 2 f 4 mm 2 wire / cable should be insulated accept a suitable named insulat, eg PVC / rubber / plastic (c) a.c. is constantly changing direction accept a.c. flows in two directions accept a.c. changes direction a.c. travels in different directions is insufficient d.c. flows in one direction only [0] M4. (a) diode accept LED (b) all symbols crect must include at least voltmeter and diode Page 26 of 33 diode allow ecf from part (a) if the component is not identified as a diode allow symbol without the line through triangle igne polarity of diode voltmeter in parallel with component added in series any additional components must not affect the ability to measure V and I f the diode / their (a) (c) (i) 0.05 accept 50 ma accept between and inclusive their (c)(i) crectly calculated gains both marks allow mark f crect transfmation and substitution allow 7 if using [6] M5. (a) (i) symbol f a diode accept symbol f a variable resist voltmeter is in series voltmeter is not in parallel ammeter is in parallel ammeter is not in series accept an answer in terms of how the circuit should be crected voltmeter and ammeter are wrong way around is insufficient (b) (i) 0.2 (V) accept any value between 0.20 and 0.2 inclusive Page 27 of 33 37.5 allow mark f I = allow 2 marks f crect substitution, ie 0.3 = R allow mark f a crect substitution using I = 0.8 I = 0.08 I = allow 2 marks f answers of (.3) 3 (c) (i) 25 allow mark f obtaining period = 0.04(s) 2 diode has large resistance in reverse / one direction so stops current flow in that / one direction allow diodes only let current flow one way / direction allow mark f the diode has half-rectified the (a.c. power) supply [2] M6. (a) (i) light dependent resist / LDR accept ldr 25 (kilohms) accept inclusive accept Ω (iii) 5 (V) their (a) crectly converted to ohms crectly calculated allow mark f converting 25 kω / their (a) to ohms allow mark f crect substitution ie (000) their (a) allow an increct conversion from kilohms providing this is clearly shown 2 (b) (i) linear scale using all of the available axis must cover the range 4-6 v their (a)(iii) - 6 v and lie within the range 0-5 inc. negative gradient line do not allow lines with both positive and negative gradients Page 28 of 33 passing through 20 lux and their (a)(iii) only sces if the first mark is awarded only sces if line does not go above 6 volts (c) (i) 37.5 (kω) their (a) + 50 % (a) crectly calculated light intensity value would be unreliable / not accurate due to variation in resistance value accept because resistance varies by ± 50 % accept tolerance of resist is too great do not accept results are not accurate [0] M7. (a) (i) 0.25 (A) 75 allow mark f converting 5 minutes to 300 seconds allow mark f crect substitution ie allow mark f an answer.25 allow mark only f their (a)(i) 300 crectly calculated 2 coulombs C do not accept c (b) any two from: fault not repaired accept if a fault was to occur larger current will (still) flow aluminium foil will not melt (if a fault) accept aluminium foil needs a higher current / charge to melt wiring will overheat / (may) cause a fire accept idea of fire hazard do not accept explode etc 2 [6] Page 29 of 33 M8. (a) (i) 50(Hz) igne any unit given any two from: (some) current flows to Earth accept ground f Earth current flows through copper braid accept current flows through the earth wire accept electricity f current in either the first second marking point but not both RCCB detects difference between current in live and neutral wire 2 (iii) can be reset accept does not need replacing faster acting accept switches circuit off faster (b) (i) allow mark f crect substitution, ie = an answer 22 gains mark coulombs / C do not accept c accept f 2 marks 8 26 kj 8.26 MJ (c) 230 their (b)(i) crectly calculated allow mark f crect substitution, ie 230 their (b)(i) allow mark f power calculated as 2530(W) increases temperature of thermist 2 changes resistance (of thermist) do not accept increases resistance (of thermist) an answer decreases resistance (of thermist) gains 2 marks [] Page 30 of 33 M9. (a) d.c. flows in (only) one direction a.c. changes direction (twice every cycle) accept a.c. constantly changing direction igne references to frequency (b) a current flows through from the live wire / metal case to the earth wire accept a current flows from live to earth do not accept on its own if the current is too high this current causes the fuse to melt accept blow f melt do not accept break / snap / blow up f melt [4] M0. (a) (i) allow mark f crect substitution, ie 6 = R 6 = 0.2 R answers of gain mark allow mark f an increct answer caused by one err only ie using 3V an increct conversion of current 2 ohm / Ω an answer 50kΩ gains 3 marks (body) resistance changes body fat/resistance affected by (many) facts accept named fact, eg age, gender, height, fitness, bone structure, muscle, drinking water related to body fat / resistance (iii) gives misleading / wrong/inaccurate value do not credit if specifically linked to a change in mass / weight (because) high water content changes body resistance accept a specific change to resistance water changes body mass is insufficient (b) (i) RCCB detects difference
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