Lab Report 3 Expirement 17

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Dec 6, 2023

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Report for Experiment #17 DC- Circuits Gabriela Martinez Lab Partner: Paige TA: October 10, 2023

Introduction Numerous circuits powering everyday household devices rely on a direct current (DC) circuit, where charged particles flow consistently in one direction. This transfer of DC current is facilitated by converting chemical energy into electrical energy. For current to flow effectively, batteries universally feature two conductive terminals. To denote polarity, the positive terminal is consistently labeled with a "+" sign. A charged battery not coonecte to a circuit maintans a constant voltage difference called the electromotive force (emf) between its terminals is defined as the ratio of work done to ϵ ∆? charge in moving from the negative to the positive terminal. ∆? ∆? ϵ = ∆? ∆? The dimension of is thus work/charge, which in units is Joule/Coulomb, a unit also called ϵ Volt(V). The current I is defined as the charge Q that flows per unit time t in a circut. 𝐼 = ∆? ∆? Electric current is quantified in Coulombs per second, known as the Ampere (A). Another crucial parameter of a battery is its capacity to deliver a total charge, denoted as Q. The device referred to as a "variable voltage supply" utilized in this experiment essentially functions as an advanced battery. It upholds a constant DC voltage disparity between two terminals and derives its energy from an AC (alternating current) electrical outlet. The electromotive force (emf) of this supply can be configured and fine-tuned by manipulating a dial or knob. A power supply is characterized by the maximum voltage and the maximu current it can deliver. The ration of voltage/current supplies to a circut is called resistance. Higher resistance means less current flow. When a positive current flows from the + terminal, through a circut element, to the - terminal . it starts out at a higher potential and end up at a lower potential. Thus theres is a voltage drop across the element.,. If a current I flows through the circut element, the ∆? resistance R of the element can be defined as ? = ∆? 𝐼 The unit of R is Volt/Ampere, which is given the name Ohm . R is is constant over a wide Ω range of currents. The Ohms law is known as the voltage drop acrosa resistor is proportional tot he current. Power P (energy/time) or work per unit of time delivered in a circut element. ∆?/∆? Units are Watt (W).

? = ∆? ∆? = ∆?𝐼 = ∆? 2 ? = 𝐼 2 ? This lab consisted of 3 investigation centered around DC circuits and their characteristics. The primary objective was to validate or refute Kirchhoff's rules pertaining to loops and junctions, which delineate how circuit components operate when arranged in series or parallel configurations. The initial investigation focused on examining the electromotive force of batteries, both individually and in series or parallel arrangements. This entailed a comparative analysis of electric potential sources in parallel and series configurations. The second investigation delved into Ohmic resistance, with the aim of substantiating Ohm's law. This was achieved by determining a resistor's actual resistance using an ohmmeter, and subsequently contrasting it with the calculated resistance derived from measurements of current and voltage. The third investigation revolved around resistor networks, specifically comparing resistors organized in series with those in parallel. The total resistance determined in the series arrangement was juxtaposed with two calculated resistance values based on Ohm's law, accounting for total voltage and total current in the context of parallel resistors. Additionally, this value was compared with that derived from Kirchhoff's junction rule for resistors in parallel. . Investigation 1 To start this investigation, commence by measuring the voltage of a single battery. Ensure that the DMM is configured to measure voltage by pressing the DC V button. Subsequently, establish a connection between the DMM, set up as a voltmeter, and the battery. Use a patch cable to link the positive + battery terminal to the DMM's positive (red) V input, and another patch cable to connect the negative - battery terminal to the DMM's negative COMM input. Refer to the circuit diagram below for guidance. Document the voltage recorded by the DMM in an Excel sheet; this value represents the electromotive force (emf) of the battery. The error for was 1% of the calculated Voltage. Reverse the lead connections and conduct the measurement once more. Repeat this process for the second battery.

Alignment Voltage of Battery 1 Error Voltage of Battery 2 Error Correct way 1.6 0.016 1.4 0.014 Reverse -1.6 0.016 -1.4 0.014 After completing the voltage measurements for both batteries, proceed to connect them in series as depicted below. Repeat the previous steps and document the voltage across the combined batteries. It's evident that the measurements deviate from the assumption of the meter's 1% precision.The error for was 1% of the calculated Voltage. Voltage of batteries in series Error 3.08 0.308 To conclude the investigation, join the two batteries in a parallel arrangement, as illustrated in the circuit diagram provided below. Gauge and document the voltage across the combination, specifically between one positive terminal and one negative terminal.The error for was 1% of the calculated Voltage. This measurement aligns with the initial reading obtained in the first step, demonstrating the same voltage. Voltage of batteries in parallel Error 1.6 0.016 In a flashlight, batteries are often arranged in series, stacked one atop the other. This configuration boosts the voltage supplied to the flashlight, resulting in a brighter illumination. On the other hand, in a remote control, batteries are typically arranged in parallel, positioned

next to each other. This setup extends the operational duration of the remote, as it consumes energy at a slower rate. . Investigation 2 To start the next investigation we need to disconnect the battery and use the DMM as an ohmeter to measure and record the actual value of the 100 resistor in the circuit box. The error for was 1% of the Ω calculated measurement. The results werent within nominal tolerance meaning the two values were inconsistent. Measurement of 100 ohm resistor Error 109.7 1.097 Next we measured and recorded the emf of one battery and used that recording from here on. The error for was 1% of the calculated measurement. emf of one battery Error 1.6 0.016 The subsequent step involved constructing a circuit for gauging the current passing through the 100 resistors arranged in a series configuration with the battery, following the provided circuit diagram. One of the DMMs will be configured to function as an ammeter. The two current terminals will be designated for 20 A maximum and the other for a lower current of 500 mA. Connect the red terminal labeled "500mA max input" and the black terminal marked "COMM" and select the DC current measurement. Once the setup is complete, proceed to measure and document the current.The error for was 1% of the calculated measurement. I (mA) error 14.25 0.1425 Adding the second DMM to our circut as a voltmeter, we measured the voltage across the the resistor. Leaving the first DMM in the circut as is. The voltage across the resistor is shown below. The error for

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