Cambridge IGCSE Physics 0625 — 2024 Oct/Nov Paper 6 · Variant 2

1 Fig. 1.1 represents a stack of glass microscope slides. stack of glass microscope slides Fig. 1.1 (not to scale) A student takes measurements from a stack of glass microscope slides in order to estimate the number of slides in the stack. The sides of the stack have been covered with tape so that the student cannot count the number of slides in the stack. Fig. 1.2 shows side views of the taped stack of slides given to the student. This figure has been drawn at full scale. stack of glass w l microscope slides covered with tape h side view side view Fig. 1.2 (a) Using Fig. 1.2, measure the length l , the width w and the height h of the covered stack of slides in centimetres to the nearest millimetre. l = ......................................................... cm w = ......................................................... cm h = ......................................................... cm [2] (b) (i) The student uses a balance to measure the mass M of the covered stack of slides. covered stack of glass microscope slides balance 57.87g Fig. 1.3 Write down the mass M of the covered slides to the nearest 0.1 g. M = ...................................................... g [1] (ii) Calculate the density ρ of the glass. Use your results from (a) and (b)(i) and the equation shown. M ρ = l wh Give the unit for your answer. ρ = ............................................................... unit = ............................................................... [2] (c) The teacher writes down the mass m and the thickness t of a single microscope slide on a piece of card, as shown in Fig. 1.4. thickness of a single slide t = 0.11 cm mass of a single slide m = 4.2 g Fig. 1.4 (i) Use your answer to (b)(i) and information from the card in Fig. 1.4 to estimate the number of microscope slides N1 in the covered stack. N1 = ......................................................... [2] (ii) Use your answer to (a) and information from the card in Fig. 1.4 to obtain another estimate of the number of microscope slides N2 in the covered stack. N2 = ......................................................... [1] (d) Two quantities can be considered to be equal within the limits of experimental accuracy if their values are within 10% of each other. State whether your values of N1 and N2 from (c)(i) and (c)(ii) can be considered equal. Support your statement with a calculation. calculation statement ............................................................................................................................ [2] (e) Suggest one reason why the estimated values of N are different. ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 11]

Mark scheme: Question Answer Marks 1(a) l = 7.5 (cm), w = 2.5 (cm), h = 1.3 (cm) 1 all values to nearest millimetre 1 1(b)(i) 57.9 (g) 1 1(b)(ii) 2.3 (754) 1 g / cm3 1 1(c)(i) N1 correctly calculated (13.7857) 1 answer given to the nearest integer rounded up or down (13 or 14) 1 1(c)(ii) N2 correct (11 or 12) (11.8181.) 1 1(d) statement matches candidate’s results 1 10% difference calculation shown using candidate’s values 1 1(e) slides not all the same mass / weight / slides not all the same thickness / the tape adds to the mass / weight / height of the 1 stack

More questions on Density

2 A student measures the resistance of a light‑emitting diode (LED) when the current in it changes. The student sets up the circuit shown in Fig. 2.1. + − 220 Ω P Q R Fig. 2.1 (a) The student: • connects a voltmeter to measure the potential difference across the 220 Ω resistor • closes the switch • records the voltmeter reading VPQ in the top row of Table 2.1 • opens the switch. (i) On Fig. 2.1, draw the symbol for a voltmeter connected to measure the potential difference across the 220 Ω resistor. [2] (ii) The voltmeter reading is shown in Fig. 2.2. 1 2 V 0 3 Fig. 2.2 Write down the reading in the top row of Table 2.1 under the heading VPQ. [1] Table 2.1 resistance between P and Q VPQ / V VQR / V I / A RLED / Ω / Ω 220 2.1 330 2.0 0.0076 263 (b) The student: • disconnects the voltmeter from points P and Q • reconnects the voltmeter across the LED between points Q and R • closes the switch. • records the voltmeter reading VQR in the top row of Table 2.1 • opens the switch. Calculate the current I in the circuit in part (a) using the equation VPQ I = R where R = 220 Ω. Record your answer in the top row of Table 2.1. [1] (c) Calculate the resistance RLED of the LED using the equation VQR RLED = I Record your answer to a suitable number of significant figures for this experiment in the top row of Table 2.1. [2] (d) The student: • removes the 220 Ω resistor from the circuit and replaces it with a 330 Ω resistor • reconnects the voltmeter across the resistor between points P and Q • repeats parts (a) to (c) for the 330 Ω resistor. Use the information in Table 2.1 to calculate the value of the potential difference VPQ across the 330 Ω resistor. Show your working and record your answer in Table 2.1. [1] (e) As the resistance between points P and Q changes, the current in the circuit changes. Use your results in Table 2.1 to write a conclusion, stating how the change in current affects the potential difference VQR across the LED and the resistance RLED of the LED. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (f) (i) Another student uses a variable resistor to control the current in the circuit. Draw the symbol for a variable resistor. [1] (ii) Explain one advantage of using a variable resistor for this purpose rather than the procedure carried out in (a) and (b). ........................................................................................................................................... ..................................................................................................................................... [1] [Total: 11]

Mark scheme: 2(a)(i) correct voltmeter symbol 1 voltmeter in parallel with the 220  resistor 1 2(a)(ii) 2.4 (V) 1 2(b) (I = 2.4 / 220 =) 0.0109 / 0.011 (A) 1 2(c) 190 / 191 / 192 / 193  or values rounding to these 1 answer expressed to 2/3 significant figures 1 2(d) 2.5 / 2.51 / 2.508 1 2(e) as the current decreases VLED decreases (or reverse) 1 and RLED increases (or reverse) 1 2(f)(i) symbol correct (See page 9 of this document for further guidance on tolerance for candidate answers for this question part). 1 2(f)(ii) avoids connecting / disconnecting the circuit / can obtain a continuous set of values / easier (to change the 1 current/resistance) / quicker / can obtain more values of resistance / current

More questions on Electric circuits

3 A student investigates the image formed by a converging lens. The apparatus is set up as shown in Fig. 3.1. screen converging lens illuminated in holder object d Fig. 3.1 (a) (i) The student: • switches on the lamp • places the lens a distance u = 20.0 cm from the illuminated object (a triangular hole in the card) • adjusts the position of the screen until a sharp image of the illuminated object is formed on the screen. Measure on Fig. 3.1, to the nearest 0.1 cm, the image distance d from the centre of the lens to the screen. d = ................................................... cm [1] (ii) Fig. 3.1 is drawn to a scale of one‑fifth (15) full size. Calculate the actual image distance v from the lens and record your value in Table 3.1. Table 3.1 object distance u image distance v / cm / cm 20.0 25.0 37.2 35.0 26.5 45.0 22.7 55.0 20.9 60.0 20.2 [1] (b) The diagram in Fig. 3.2 shows the illuminated object and its image drawn full size when u = 20.0 cm. illuminated object image Fig. 3.2 (i) State two ways in which the image differs from the object. 1 ........................................................................................................................................ 2 ........................................................................................................................................ [1] (ii) The magnification m of the image can be calculated using the equation shown. v m = u Use your answer to (a)(ii) to calculate the magnification m of the image. m = ......................................................... [1] (c) The student repeats the procedure in (a)(i) for values of u = 25.0 cm, u = 35.0 cm, u = 45.0 cm, u = 55.0 cm and u = 60.0 cm. The student’s results are shown in Table 3.1. Plot a graph of v / cm (y‑axis) against u / cm (x‑axis). Draw the best‑fit curve. [3] 60 50 40 30 20 10 0 0 10 20 30 40 50 60 (d) Use your graph to find the value of v when u = 30.0 cm. Show clearly on the graph how you obtained the necessary information. v = ................................................... cm [2] uv (e) The focal length f of the lens can be found using the equation f = (u + v). Use the values of u and v from (d) to calculate the focal length of the lens. f = ................................................... cm [1] (f) State one technique you use when doing the experiment to ensure that the image on the screen is as clearly focussed as possible. ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 11]

Mark scheme: 3(a)(i) d = 12.1 (cm) 1 3(a)(ii) 60.5 (cm) 1 3(b)(i) image is inverted / upside down and 1 image is bigger / magnified 3(b)(ii) 3.0(25) 1 3(c) axes labelled with units 1 plots correct to  ½ small square 1 good best-fit curve judgement, thin, continuous line 1 3(d) method shown on graph 1 candidate’s value of v for u = 30.0 cm read correctly from the graph to  ½ small square 1 3(e) f in the range 14.0 (cm) to 16.0 (cm) inclusive 1 3(f) move screen slowly / to and fro (owtte) / carry out experiment in a darkened part of the laboratory / use a brighter object 1

More questions on Light

4 Hot water is poured into a glass beaker and allowed to cool down. Plan an experiment to investigate how the rate at which the water cools depends upon the diameter of the water surface exposed to the air. You are provided with: • a supply of hot water • a set of glass beakers of different sizes • a measuring cylinder. You may use any other common laboratory apparatus. In your plan, include: • any other apparatus needed • a brief description of the method, including what you will measure and how you will make sure your measurements are accurate • the key variables you will control • a results table to record your measurements (you are not required to enter any readings in the table) • how you will process your results to reach a conclusion. You may include a labelled diagram if you wish. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [7]

Mark scheme: 4 MP1 additional apparatus 1 stopwatch and thermometer and ruler / measuring tape / callipers MP2 method 1 MP3 time hot water (in beaker) cooling repeat using beakers of different diameter / size MP4 control variables 1 one from: volume / mass of water initial temperature of the water / beaker time of cooling or the same temperature decrease MP5 results table 1 columns for diameter / d and time / t or diameter / d and temperature /  with correct units MP6 conclusion 1 plot a graph of diameter vs time / plot a graph of diameter vs temperature (decrease) / plot a graph of diameter vs rate of cooling / plot graphs of temperature against time (for each beaker) / compare the results to see if / how the diameter affects the rate of cooling / compare the temperature decreases – largest decrease gives the greatest rate / compare the times – least time gives the greatest rate / calculate the rate of temperature decrease for each beaker and compare MP7 additional point (one from): 1 another control variable stated at least five sets of data taken repeat each measurement and take an average Q2(f)(i) Symbol for variable resistor: The box must be a rectangle, not a square. The arrow must lie tilted between the longer sides. It doesn’t matter which way it tilts, or which way up it is. The arrowhead must emerge from the rectangle. The tail of the arrow must at least reach the opposite side of the rectangle, but do not penalise if it stops there. The two lines showing connection to the rest of the circuit are not required but if present must be correct. This type of arrowhead is also acceptable. BOD NBOD NBOD The following symbols are all incorrect:

More questions on Transfer of thermal energy