# A nichrome copper wire is 3m long and has a uniform

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Unformatted text preview: s 3m long and has a uniform cross-sectional area of 10,6m2 . When connected to a potential di erence of 12V , a current of 40A develops in the wire. The RESISTIVITY of this material is, A 1 10,7 m correct B 2 10,7 m C 1 10,6 m D 2 107 m E 1 107 m 3 7. A capacitor of capacitance C is connected to a battery of voltage V through a resistor R. The current goes as V=R exp,t= where is the time constant of the circuit. At the end of one time constant, the charge has reached a value 63 of what it will be when t ! 1. How much is the charge after two time constants have passed? A 39:7 B 86:5 correct C 13:5 D 23:3 E Need more data to answer 8. A portion of a circuit is shown, with the values of the currents given for some branches. What is the direction and value of the current i? A , 3A B ", 3A 1A 8A 5A C , 4A D ", 4A E , 7A correct 3A i 2A 4 9. If in the circuit below, the potential at point A is de ned to be VA = 40V , what is the potential at point B ? A VB = 18V 4 B VB = 21V C VB = 41V D VB = 32V correct 20V 15V E VB = 53V 1 10. The equivalent resistance between points 1 and 2 of the circuit shown is, A 4:5 1 1 B 6 1 C 2 D 3 1 4 5 E 2:5 correct 2 2 2 5 11. In the circuit shown, both resistors have the same value, 5 , the capacitor has capacitance 10F and the battery is a regular 1:5V battery. Suppose the switch has been closed for a long time, and is suddenly opened. What is the time constant of the circuit after the switch is opened? A 2 10,4s R B 1 10,4s correct C 5 10,5s S D 50s E 100s V C R 12. The current in the 6 resistor in the shown circuit is, A 2A 6 12V B 4A 4 C 6A 12 D 1A correct E 0:5A 8 6 13. A wire of 1m in length and mass 20g is suspended from an insulator block by a pair of massless exible leads in a magnetic eld of 0:4T , as shown in the gure. What are the magnitude and direction of...
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