Lab Electric Current and Related Variables Assignment Instructions

ENGR 115 L AB : E LECTRIC C URRENT AND R ELATED V ARIABLES A SSIGNMENT I NSTRUCTIONS I NSTRUCTIONS Lab assignments are intended to give you some ‘hands on’ experience in applying the concepts introduced in the course text. They are designed to get you out of your classroom or office and develop the skills of designing experiments and collecting data, and then performing calculations, evaluating the results, and communicating your findings. Labs are more than just number crunching – they are about reflecting on what is both practical and technically sound engineering problem-solving. For each problem below, address the scenario presented and develop engineering solutions. Communicate your results using drawings, pictures, and discussion, supported by calculations developed using the Microsoft Equation Editor or a similar tool. Submit your lab report in a single pdf file uploaded to the location provided in Canvas before the due date/time indicated. Each problem should be treated as a micro-report with a problem statement, calculations/work shown to support your solution, and a conclusion/reflection on your findings. P ROBLEMS 1. Investigate the size and the material used for heating elements in the following products: a toaster, a hair dryer, a pressing iron, a coffeemaker, and an electric stovetop. Discuss your findings in a brief report. 2. Obtain information about the electric current and voltage ratings of your residential building or a building belonging to someone you know. Draw a diagram showing the power distribution, similar to Figure 12.15 of the Moaveni text. 3. Contact your electric utility company and obtain information on what the company charges for each kilowatt-hour usage (kWh). Estimate the cost of your electric power consumption for a typical month. Make a list of your activities for the month and estimate the power consumption for the devices you used. Write a brief report discussing your findings. 4. Friction is a significant cause of wasted energy in a system. Using an inclined plane method, we will measure the kinetic friction coefficient for your unpowered MTC. This method will measure the overall rolling coefficient of friction in your MTC. The MTC will roll down the ramp using only the potential energy available to the car on the ramp. Do not engage the spring for these trials. Page 1 of 3

ENGR 115 a. Build the ramp configuration for this technique as follows: Where, H = vertical height of the end of the ramp from the horizontal surface L r = ramp length = total length of the ramp L s = start distance = distance from the MTC starting point to the end of the ramp L c = coast distance = distance from the end of the ramp until the MTC reaches a stop 𝜃 = ramp angle = angle between the ramp and the horizontal surface Note: the ramp and floor should have a low friction surface; the transition between the ramp and floor should be smooth. Be consistent in your measurement units and on the point where you take physical measurements on the MTC. b. Calculate θ : θ = arcsin ( H Lr ) c. Roll your MTC down the ramp five times and take the average L c . d. Calculate the Kinetic Coefficient of Friction, µ, using the formula: μ = tan ( θ ) / [ Lc Ls× cos ( θ ) 3 ❑ + 1 ] e. Show your calculations with units and develop a table like the one below with calculations, and measurements for variables H, Lc, Lr, Ls, Ɵ, and µ. Reflect on what Page 2 of 3 H L r L s L c Ɵ