2 Which arrangement of identical resistors would draw the most current when connected to the same potential difference?

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1 Show all necessary workings for multiple choice. Current Electricity Assignment 2 Name: 1 A circuit consists of a battery and three resistors. The resistors are of unequal value and are connected in parallel. What is equal to the sum of the currents through the resistors? the current through the battery the current through one resistor three times the current through one resistor zero 2 Which arrangement of identical resistors would draw the most current when connected to the same potential difference? 3 If R 9 > R 10 then which statement concerning the circuit would be correct? No current would flow through R 9; it would all go through R 10. The current through the two resistors is the same regardless of the resistance. The current through R 9 is less than the current through R 10. The current through R 9 is greater than the current through R. 4 When switch, S is open to shut off bulb 2 in the figure to the right bulb 1 will get brighter. bulb 1 will get dimmer. bulb 1 will not be affected. bulb 1 will also be shut off What is the total resistance between points A and B, as shown in the picture? Each resistor is rated at If four 20 resistors are connected in parallel, what is the equivalent resistance?

2 7 A circuit contains 2 resistors connected to a battery as shown in the figure. The current leaving the battery is 0.50 A. What is the potential difference of the battery? 0.10 V 2.5 V 5.0 V 10.0 V 8 Two resistors are arranged in a circuit that carries a total current of 15 A as shown in thefigure. Which of the entries in the following table is correct? 9 A 36 volt battery, a small lamp, and a resistor of 2.0 are connected as shown in the picture. The total current in the circuit is 3.0 A. What is the resistance R of the small lamp? A series circuit consists of a battery and three resistors arranged as shown in the diagram below. What is the potential difference Vxy? 3.0 V 6.0 V 9.0 V 21 V 11 Which best describes the relationship between the two circuits below if all resistors are identical, V 1 and V are readings from ideal voltmeters, and I and I are readings from ideal ammeters? 2 1 2

3 12 For the circuit shown below, what is the effect on the ammeter and voltmeter readings when the switch is closed? Ammeter reading Voltmeter reading decreases decreases decreases increases increases decreases increases increases 13 A toaster is already plugged in to an electrical outlet. What will happen to the current if the circuit of a lamp is plugged into the same outlet? It will decrease. It will increase. It will remain the same. The answer depends on the power rating of the lamp. 14 A 120 V power line is protected by a 15 A fuse. What is the maximum number of 500 W lamps that can be connected in parallel on the circuit? What happens to the power dissipated by a circuit of constant resistance if the voltage across the circuit is doubled? (Be careful!) decreases to one half its original value decreases to one quarter its original value doubles quadruples 16 How much electrical energy does a 75 W motor use in 15 minutes? J J J J 17 A refrigerator compressor draws 2.0 A from a 120 V source and operates, on average, 30 min/h. What is the approximate hourly cost of operation the refrigerator if the cost of electrical energy is 8 /kwh? A resistor dissipates 1.5 W when it is connected to a battery with a potnetial difference of 12 V. What is the resistance of the resistor? If a W hair dryer has a 10.0 resistance, how much current will it draw? A 11 A 12 A 120 A

4 20 What is the power dissipated by the 5.0 resistor in the circuit to the right? 3.5 W 4.2 W 7.2 W 130 W 21 Two resistors have the same power dissipated by them. The potential drop across resistor A is twice that across resistor B. If the resistance of resistor B is R, what is the resistance of A? R/2 R 2R 4R 22 A 12 V battery is connected in a circuit that contains twenty-four resistors in parallel. What is the current through each resistor? {2} 23 How could four identical light bulbs be wired to a 12 V battery in a circuit to achieve each of the following? {3} Maximum current is drawn from the battery. Maximum electrical resistance is achieved. Light will still be produced even if one of the lights blow. 24 Use the circuit diagram below to answer the questions that follow. (assume 2 sig figs) What is the equivalent resistance between the points A and B? {2} What is the current through the 2 resistor? {4}

5 25 A 39 V source is connected to three resistors as shown in the picture. Find the total resistance of the circuit. {2} The total current in the circuit. {1} The potential difference across R 3. {3} The power dissipated in R 3. {2} 26 The picture shows a series-parallel combination of 5 resistors connected to a battery with a potential difference of 8.0 V. Use the values indicated in the figure to find each quantity. The current through R 4. {3} The voltage drop across R 1. {3}

6 27 Four resistors and a 26 V power supply are arranged as shown in the circuit diagram. (a) Determine the equivalent resistance for this circuit. {3} (b) Find the current through R3. {6} 28 A home owner wants to put Christmas tree lights on his house. The string has 300 lights, with each light rated at 25 W. If the homeowner runs the lights for 3 weeks at 6 hours each day, how much will it cost him to operate the lights? The price of electrical energy is 7 / kwh. {4} 29 A circuit consists of 50 lights, each with a resistance of 4.5, connected in parallel with a 120 V source. What is the total power dissipated in the circuit? {3} 30 A hair dryer with a power rating of 2200W is plugged into a 120V outlet. This outlet is protected by a 15 A fuse. a) Will the fuse blow? Show calculations to support your answer. {2} b) Explain whether or not it would be a good idea to replace the 15A fuse with a 20A fuse. {2}