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Name:       Evelyn                                       Class:       8.6                                        Date:  Friday 26th JanuaryLab Partners:     Rico, Shraddha (only for conducting the experiment)How current is impacted by the length of the wire Introduction: This should be a paragraph that introduces the background scientific theory of the investigation and includes the context/relevance (you must do research (a citation is needed)) – and in this process, you will develop an understanding of all variables that may affect the dependent).In this lab I will be investigating how the length of the wire impacts the current. This experiment is to find the relationship between the length of the wire and the current. Electricity travels through the circuit via wire which accommodates electric current, which carries energy. When we increase the length of the wire, there are more ions in the wire and a longer distance for the electrons to travel. Therefore, V = I x R. If we keep the voltage constant and change the length of the wire which changes the resistance, we can expect that if the resistance is higher, then the current is lower, and vice versa. In this lab we will learn about how the length of the wire impacts it’s resistance, and therefore it’s current.                                                   Aim:                     Written in the form, “To investigate the effect of the independent variable on the dependent variable.”The aim of this experiment is to investigate the effect of the length of a wire kept constant in thickness and material on the electric current through the circuit. Hypothesis:      A concise statement of what you think will happen, with scientific reasoning (a citation is needed).  We normally start with, “It is predicted that…because…”It is predicted that the longer the wire is, the lower the current will be. This is because the longer the wire, the more atoms there are for the electrons to move around and bump into, therefore slowing the current. (BBC Bitesize, n.d)Fair Testing:      Make a table to show how you will measure/control all variables to make it a fair test.Independent variableHow will it be manipulated? (range and increment)Length of WireStarting out at 5 cm, we will finish at 30cm and increase the length by 5 cm every time. Dependent variableHow will it be measured?Current The current will be measured in every 5 cm increment with an ammeter. Controlled variablesHow will it be kept constant? (value if applicable)Why does it need to be controlled?Thickness of wireWe will use only the wire provided, so the thickness will always be constant. Because the thickness of the wire has an effect on the resistance of the wire, which then affects the current.  Type of wire material We will only use constantine wire, which will be provided Because the type of wire (copper, lead etc) has an effect on the resistance of the wire, which then in turn affects the current of the wire. Amount of sources usedWe will use a two batteries with three volts in total. Because voltage and current are directly proportionate, we need to keep the voltage constant so that the length of the wire and only the length of the wire impacts the current. Apparatus:        A detailed list of equipment required, with a labelled 2D diagram of the set-up.Constantine wireBattery packLight bulbMeter stickRubber coated wireCrocodile clipsTapeMultimeterMethod:            What you will do step-by-step (make a numbered list), explaining clearly how the independent variable will be set and controlled.  Also, clearly detail how the dependentvariable will be measured.  Should begin with “Set-up apparatus as shown in the Diagram.”Set up apparatus as shown in diagram. Clip one crocodile clip at 0 cm and the other to 5 cmTake dataRepeat steps 2 to 3 in 5 cm increments until the 2nd crocodile clip is at 30 cmRepeat step 2 through 4 twice to get three trials Safety                  What safety precautions you will take.  Begin with a first line of “All general labConsiderations: safety rules will be followed.All general lab safety rules will be followed. In this experiment, we will take extra care to make sure the voltage is set correctly so that the light bulb does not blow. As with any electrical experiment, we run a risk of an electric fire, so it is important that we do not leave any experiment unattended.Data Collection:Include a data table for all quantitative data and qualitative data.The table must include headings with units and the first column should be for the independent variable, while the other columns for multiple trials of the dependent variable. Independent variable/unitsTrial 1Trial 2Trial 3Qualitative observations5 cm 2.5 mA 2.46 mA2.46 mAThe light bulb is bright and consistent. 10 cm 2.48 mA2.46 mA2.45 mA Still bright and consistent15 cm2.45 mA2.45 mA2.44 mAStill bright and consistent but is a little bit less bright 20 cm2.44 mA2.42 mA2.43 mAConsistent and moderately bright25 cm2.36 mA2.41 mA2.43 mAConsistent and moderately bright. 30 cm2.26 mA2.40 mA2.40 mAThe light bulb was slightly but noticeably dimmer than when the wire was 5 cm long. When I disassembled the setup, the wire was warm but not hot. Data Processing:  This includes three parts. 1.     A new table which shows processed data. Length of wire/cmCurrent/mA52.47102.46152.44202.43252.40302.352.     Sample Calculations – Include a sample of each calculation that was done.  The sample needs to include a general equation, an equation with plugged in data, and a final answer with units.General equation: (trial 1 + trial 2 + trial 3)                                                     3Sample with plugged in data – 5cm: (2.5 + 2.46 + 2.46)    =  2.47 mA                                                                               3Sample with plugged in data – 10cm: (2.48 + 2.46 + 2.45)    =  2.46 mA                                                                                                                                                                               3Sample with plugged in data – 15cm: (2.45 + 2.45 + 2.44)  = 2.44 mA                                                                                   3Sample with plugged in data – 20cm: (2.44 + 2.42 + 2.43) = 2.43 mA                                                                                   3Sample with plugged in data – 25cm: (2.36 + 2.41 + 2.43) = 2.40 mA                                                                                   3Sample with plugged in data – 30cm: (2.26 + 2.40 + 2.40) = 2.35 mA                                                                                   33.     Graph – Draw a linear graph (called a Scatter Chart in Sheets, Numbers, and Excel) whenever your dependent variable varies according to the independent variable.  Bar and pie graphs may be used when the data is counted or forms parts of a whole.-        Note that the graph must have a logical scale (pages likes to use odd scales, which you must change) include major and minor gridlines, a title, labelled axes with units, and a best fit trendline.  The equation does not need to be included, but may provide a more clear idea of the relationship.Conclusion: Write a clear paragraph that:-        Fully answers the aim, fits the data, and is justified by using correct scientific reasoning (a citation is needed) by making a detailed, correct reference to the data.-        Makes a fully explained and justified comment on the strength of the relationship between the pattern discussed above and the original hypothesis.In this lab investigation, we found out that the longer the wire was, the less current there is. This is because the longer the wire, the higher the resistance due to the length the electrons have to travel and more ions blocking the way of the current. Because resistance and current are inversely proportional, we see that the longer the wire, the higher the resistance and the lower the current. (The Physics Classroom, n.d) The original hypothesis was that the longer the wire got, the lower the current because of the resistance. This is proven true in this lab due to the proportional relationship between length of wire and the inversely proportional relationship between resistance and current. Evaluation:  this includes two parts1.     A brief evaluation paragraph that:-        Makes appropriate reference to the reliability and precision of data by comparing trials and looking at the trend (identifying anomalies where present).-        Through this, you should explain that this shows that there are uncertainties present.2.     A table that outlines the uncertainty (example below).When we look at the data, we can identify some anomalies. For example in the length of the wire 30cm, the first trial was 2.26 mA, while the second and third trial was 2.40 mA. To make this experiment more reliable in the future, we could switch the batteries as we go along or make sure the batteries are fully charged to start with. To investigate these problems in more depth, we can do the experiment a few more times and change one thing at a time so that we can identify the main problems. Source of UncertaintyEffect on DataImprovement Voltage to begin withSince voltage and current are directly proportional, we want to make sure that the voltage stays about the same throughout so that the only thing that affects the current is the length of the constantine wire. Check that the batteries are full to begin with and check throughout the experiment to make sure they are around the same voltage when they were full. If not, change the batteries or switch to using a different battery in the battery pack. Heat of the wireBecause of the resistance, the wire can heat up, which then in turn affects the resistance. This is because as the wire gets hotter the ions inside  vibrate more, causing more collisions with the electrons, which increases resistance. When we are writing down measurements or are in between measurements, we can break one part of the circuit then reconnect it when we are ready to take data again. How taut the wire is on the meter stick If the wire is not taut on the meter stick, the length would be a bit longer wherever we clip it unless it’s at zero. Take our time to tape down the wire and make it taut so that our measurements are accurate and with the exact length we want.

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