University:
California State University, Northridge
Course:
PHYS 100A | General Physics I
Academic year:

2024
Views:

109

Pages:

6
Author:

Hallie Randolph

Faraday’s Law PRE-LAB QUESTIONS 1. Analyze Graph 1 and rank the change in magnetic flux during Times A, B, C, D, and E from least to greatest. Use an equal sign to designate equal magnetic fluxes. a. Magnetic flux is given by dB/dt, which is the same as the slope of the below graph. A and B have the same positive slope, C and E both have a slope of zero and D has a negative slope. D r=3cm or .03 m -> A=pi(.03) d. IρL/pi (.032)I=.2uA: ((.2*10-6)*(1.68*10-8)*(.9)/(pi*(.03 2) Faraday’s Law EXPERIMENT 2: BUILDING A SIMPLE ELECTRIC MOTOR Post-Lab Questions 1. What orientation of the coil (vertical or horizontal) allows current to flow through the assembly? What happens as you rotate the coil 180º from this position? Explain your answer. a. b. c. Thus, when theta = 0 or 180, then only emf is generated in the coil. Orientation should be horizontal. When coil is rotated in 180 from the position, the sign of emf generated changes. 2. Explain what would happen if both tails of the wire coil had all of the insulation scraped off. a. The scrapping off the insulation from both tails helps to flow the current generated due to Faraday rotation emf. 3. Analyze the motor design and list three variables in the experiment that if changed will increase or decrease the speed at which the coil rotates. Explain your reasoning. a. The increase or decrease in the speed of coil is related to emf generated in the coil. Thus, from the above equation, the variables are B, A, and theta. 4. Given the strength of the battery and the size of the coil, there are an ideal number of coil turns that make a motor spin at high speeds without being unstable. Critique a motor design constructed with a coil of 50 coils of wire instead of 15 coils. Use your results to support your critique. a. b. Where N is number of turns. Thus, when motor is constructed with a greater number of coils, more emf is generated. If coil number is less, less emf is generated.