An electronic device designed to operate at any temperature in the range from -10.7C to 59.3.C contains pure carbon resistors. What is the percent difference in resistance over this range? The temperature coefficient of resistivity for carbon is -0.500 x 10-3/C. 0.2489 X What is the expression that gives the temperature dependence of resistance? How can you use the difference in resistance and the average resistance to find the percent difference? %Consider a portion of a cell membrane that has a thickness of 7.50 nm and 1.9 um x 1.9 um in area. A measurement of the potential difference across the inner and outer surfaces of the membrane gives a reading of 97.6 mV. The resistivity of the membrane material is 1.30 x 10/ 0 . m. (a) Determine the amount of current that flows through this portion of the membrane. 8 X What is the resistance of the membrane? Which side of the membrane contributes to its resistance? Which sides of the membrane contribute to the cross sectional area of the membrane? A (b) By what factor does the current change if the side dimensions of the membrane portion is halved? The other values do not change. decrease by a factor of 8 O increase by a factor of 4 O increase by a factor of 2 O decrease by a factor of 2 O decrease by a factor of 4 XA copper wire has a resistance of 0.530 0 at 20.0C, and an iron wire has a resistance of 0.559 0 at the same temperature. At what temperature are their resistances equal? The temperature coefficient of resistivity for copper is 3.90 x 10-3(C)-1 and for iron it is 5.00 x 10-3(C)-1. OC[a]: What is the wavelength of 136-MHZ radio waves used in an MRI unit? x What is the relationship between the wavelength and the frequency of light? m [b] If the frequencies are swept over a :1.55% range centered on 136 MHZ, what is the range of wavelengths broadcast? minimum x Is the minimum less than or more than the average wavelength? In . 4 mamum it Is the maximum less than or more than the average wavelength? m You've entered the Great Space Race. Your engines are hearty enough to keep you in second place. While racing, the person in front of you begins to have engine troubles and turns on his emergency lights that emit at a frequency of 5.750 x 1014 Hz. If the person in front of you is traveling 2635 km/s faster than you when he turns on his lights, what is the frequency of the emergency lights that you observe when it reaches you in your spaceship? (Enter your answer to four significant figures.) 4.0 4 X What relationship describes the frequency of a wave for an observer that is moving relative to the source? Hz