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ELECTRICAL AND MAGNETIC PROPERTIES OF MATERIALS - A Review for Exams

This video is a compendium of exam questions that frequently appear on exams for electrical engineers covering the topic of Electrical and Magnetic Properties of Materials. LIST OF QUESTIONS 00:00:00 Question 1 00:18:10 Question 2 00:24:30 Question 3 00:32:09 Question 4 00:39:36 Question 5 00:45:10 Question 6 00:51:04 Question 7 00:59:38 Question 8 01:04:57 Question 9 01:16:19 Question 10 01:19:43 Question 11 01:28:12 Question 12 01:32:59 Question 13 01:36:59 Question 14 01:39:50 Question 15 01:43:53 Question 16 QUESTION HEADINGS Question 1: Design a power transmission cable 100Km long that will carry a current of 200A with no more than a) 500KW and b) 50KW of power loss. Question 2: Assuming that all of the valence electrons contribute to current flow, a) calculate the mobility of an electron in copper, and b) calculate the average drift velocity for electrons in a 10m wire when 50V is applied. Question 3: Calculate the electrical conductivity of pure copper at a) 400°C and b) -100°C. Question 4: Calculate the theoretical magnetization limit of Iron, and compare this value with the 2.1T observed experimentally. Question 5: Select a material for the production of a coil with flux density of at least 0.2T when a 10mA current flows through the conductor. Due to space limitations the solenoid should have a turns density of 1000 turns per meter. Question 6: Given the vector current density J, a) find the current density at point P, and b) determine the current flowing outwards through the circular band. DATA ON THE BOARD. Question 7: Find the resistance of a 1 mile length of copper wire, which has a diameter of 0.0508 inches. Question 8: Calculate the capacitance of a parallel-plate capacitor having a mica dielectric, a plate area of 10in2, and a separation of 0.01in. Question 9: Calculate the self-inductances of and the mutual inductances between two coaxial solenoids of radius R1 and R2 with carrying I1 and I2 with n1 and n2 turns/meter respectively. Question 10: A parallel-plate capacitor has circular plates of 8.2cm radius and 1.3mm separation. a) Calculate the capacitance, and b) what charge will appear on the plates if a potential difference of 120V is applied? Question 11: For the circuit of the figure, find the equivalent capacitance. Question 12: Two coils have mutual inductance of 325microH. What is the emf in the second coil if a) the current in the first coil increases at a uniform rate of 820A/s, and b) the current waveform is 830cos(2pi60t). Question 13: A heating element consists of two wires of different materials connected in series. At 20°C the two wires have resistances of 600ohms and 300ohms and average temperature coefficients of 0.001/°C and 0.004/°C, respectively. What is the heating element's total resistance at 50°C? Question 14: A solid, cylindrical, copper conductor has a length 1000m, a resistance of 0.225ohms, and a resistivity of 1.77x10^-8 ohms.m. What is the diameter of the conductor? Question 15: For operation at 60Hz and a given peak flux density, the core loss of a given core is 1W due to hysterises and 0.5W due to eddy currents. Estimate the core loss for 400Hz operation with the same peak flux density. Question 16: What considerations are important to minimize losses due to hysterises and eddy currents? =================== To contact me send message to my WhatsApp: +55 32 999 163 417 Para entrar em contato comigo envie mensagem para meu WhatsApp: +55 32 999 163 417