a) A circuit consists of a 12 V battery connected to a switch, which is connecte
ID: 2089861 • Letter: A
Question
a) A circuit consists of a 12 V battery connected to a switch, which is connected to a light bulb of resistance 120 ? and then back to the battery. If the switch is open, which statement is true of I (the current through the switch and Vs (the difference in potential across the poles of the switch)? b) A long wire with measurable resistance is connected to a battery of potential difference V, and the current is I. The voltage is now doubled, but a fan keeps the the temperature of the wire from increasing. What will happen to the current I and the resistivity of the wire ?? c) Seven identical wires of measurable resistance are attached consecutively to a battery of potential difference V: one end of the first wire is connected to the positive terminal of the battery; the other end of the first wire is connected to one end of the second wire; the other end of the second wire is connected to one end of the third wire, and so on. The free end of the seventh wire is connected to the negative terminal of the battery. The potential difference across wire 1 is V1, and the current flowing through wire 1 is I1, If an eighth identical wire is introduced between the seventh wire and the battery, what happens to V1 and I1? d) Now, seven identical wires of measurable resistance are connected across the the terminals of the battery of potential difference V. (In other words: one end of each wire is connected to the positive terminal of the battery, and the other end is connected to the negative terminal of the battery.) The potential difference across wire 1 is V1, and the current flowing through wire 1 is I1, If an eighth identical wire is now added so it connected like the others (across the battery), what happens to V1 and I1? Suppose a 24.6 V battery is connected to a long cylindrical wire, and a current of 4.65 A flows. a) How many electrons will pass a given point in the wire every second? electrons b) What is the total resistance of the wire? ? c) If the wire is 64.5 m long, and its diameter is 0.0801 cm, find the resistivity of the wire. ?-m d) Find the work done by this battery to push one electron through the entire length of the wire.Explanation / Answer
a.) "True statement : the current through the switch". Reason : switch makes circuit open or closed . (switch open,then circuit is called Open circuit where no current flows and vice versa for closed circuit)... (b.) Resistivity of wire is material dependent and temperature dependent .Here assuming temperature remains same and geometry of wire doesnot change because of heat generated .Therefore,"resistivity of wire remains same and current doubles... (c). Case1: I1 = V/7R and V1= I1*R= V/7. Case2: I1 = V/8R and V1=i1*R = V/8. Therefore V1 and I1 both decrease when eighth wire is introduced... (d). These are in parallel V1 and I1 are independent of number of resistors. V1 and I1 remain same. (e).Q= I*t = 4.65 * 1 = 4.65 C = 4.65 * 6.241
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