PHYSICS 3204 PUBLIC EXAM QUESTIONS (Electric Circuits)

Transcription

1 PHYSICS 3204 PUBLIC EXAM QUESTIONS (Electric Circuits) NAME: August What is the instrument used to measure electric current? (A) ammeter (B) galvanometer (C) ohmmeter (D) voltmeter 27. Which type of energy is converted to electrical energy using a piezo-electric device? (A) chemical (B) light (C) mechanical (D) thermal 28. A 6.0 and a 12 resistor are connected in series to a 36 V battery. What power is dissipated by the 6.0 resistor? (A) 6.0 W (B) 12 W (C) 24 W (D) 48 W What is the resistance of a 1.0 m long copper wire of radius m ( = 1.69 x 10 m)? (A) 1.1 x 10 (B) 3.3 x 10 (C) 2.1 x 10 (D) 1.2 x What value of R in the circuit below will cause the parallel combination to dissipate the same power as the 4.0 resistor? (A) 0.26 (B) 2.9 (C) 6.0 (D) Which is equivalent to 1 W? (A) 1 V/A (B) 1 A (C) 1 V A (D) 1 V/ 5% 52.(c) In the circuit shown, calculate: i) the voltage for R4. ii) the value of R1. iii) the power dissipated in R3.

2 June What amount of energy is gained by a proton that moves through a potential difference of 1.0 V? (A) 2.7 x10 J (B) 1.6 x10 J (C) 1.4 x10 J (D) 6.3 x10 J 27. The graph provided represents voltage and current data for a resistor R. What is the resistance of R? (A) 0.50 (B) 2.0 (C) 4.5 (D) What is the resistance of a 25 W soldering iron that runs on 110 V? (A) (B) 4.4 (C) 480 (D) How does the resistance of two copper wires compare if wire X has twice the length and twice the cross-sectional area of wire Y? (A) Wire X has half the resistance of wire Y. (C) Wire X has the same resistance as wire Y. (B) Wire X has four times the resistance of wire Y. (D) Wire X has twice the resistance of wire Y. 30. What is the equivalent resistance of four 16 resistors connected in parallel? (A) 0.25 (B) 4.0 (C) 16 (D) What is the voltage drop across R1 in the circuit below? (A) 4.5 V (B) 9.0 V (C) 11 V (D) 15 V 32. Three identical resistors shown below each have resistance R. What is the total resistance of the arrangement as shown? (A) 2/3 R (B) R (C) 3/2 R (D) 3 R

3 5% 52.(c) In the circuit shown: i) calculate the total resistance. ii) calculate the voltage across resistor 2. iii) determine whether the fuse will blow. August What energy is transferred by a 6.0 V battery to run an appliance that draws 2.0 A of current in 1.0 minute? (A) 3.0 J (B) 12 J (C) 180 J (D) 720 J 27. What will be the new resistance if the radius of a piece of copper wire having resistance R is doubled? (A) ¼ R (B) ½ R (C) 2 R (D) 4 R 28. What charge flows past a point in a wire in 6.0 s if the wire carries a current of 2.0 A? (A) 0.33 C (B) 3.0 C (C) 12 C (D) 24 C 29. What is the potential difference across a 2.5 Ù resistor that carries 3.0 A of current? (A) 0.83 V (B) 1.2 V (C) 5.5 V (D) 7.5 V 30. What is the voltage drop across one of three identical resistors that are connected in series to a 6.0 V source? (A) 2.0 V (B) 3.0 V (C) 6.0 V (D) 18 V T 31. What is the voltage, V, across the source in the circuit below? (A) 2.2 V (B) 11.0 V (C) 14.0 V (D) 20.0 V Page 3

4 32. What resistor, R, must be added to the circuit below to give a total resistance of 2.00? (A) (B) (C) 1.25 (D) Which arrangement of four identical resistors has the least total resistance? (A) (B) (C) (D) 34. What are the correct units for electric potential? (A) J/s (B) J/C (C) N/m (D) N/C 35. What is the power rating of an electric kettle that draws a 12.5 A current in a 120 V circuit? (A) 0.10 W (B) 9.6 W (C) 1200 W (D) 1500 W 6% 52.(c) For the circuit below calculate: i) the value of R2. ii) the power dissipated in R4. iii) the voltage across the source. iv) Explain how the addition of another resistor in parallel will change the total resistance of the circuit. June If a circuit element can withstand a maximum current of 15 A, how many electrons can pass through it each second? (A) (B) (C) (D) Page 4

5 29. What potential difference must be applied to a 26 resistor to cause a current of 0.50 A to flow through it? (A) 6.5 V (B) 13 V (C) 26 V (D) 52 V Copper has a resistivity of m. What is the resistance of a piece of copper wire of 6 2 length 4.5 m and cross-sectional area m? (A) (B) (C) (D) What is the voltage, V, across the source for the circuit below? (A) 1.1 V (B) 4.0 V (C) 6.0 V (D) 12.0 V 32. What current, I, is coming from the source in the circuit below? (A) 0.10 A (B) 0.95 A (C) 1.1 A (D) 9.8 A 33. What is the total resistance between points X and Y below (A) 3.33 (B) 6.67 (C) 15.0 (D) 30.0 Page 5

6 34. What value of resistor, R, must be added in the circuit below to give a total resistance of 32? (A) 2.0 (B) 8.0 (C) 16 (D) 26 5% 52 (b) For the circuit shown below, calculate: i) the resistance of R1. ii) the power dissipated in R4. iii) the voltage drop across R2. 3% 52.(c) An electrical appliance runs from a 240 V power supply. A graph of power versus time for this appliance is shown below. i) Use the graph to determine the energy dissipated by the appliance in the first seconds. ii) Determine the resistance of the appliance when its power consumption is W. Page 6

7 August Which circuit is correctly wired to measure both the current and the voltage for the 3 resistor? (A) (B) (C) (D) 29. Which is always true for resistors in parallel and resistors in series? Resistors in Parallel Resistors in Series (A) equal currents equal currents (B) equal currents equal voltage drops (C) equal voltage drops equal currents (D) equal voltage drops equal voltage drops 30. If two 75 resistors are connected in parallel with an 18 V battery, how much current passes through one of the resistors? (A) 0.12 A (B) 0.24 A (C) 0.48 A (D) 4.2 A 31. The diagram below shows part of an electric circuit. What is the current through resistor R1? (A) 1.0 A (B) 1.4 A (C) 2.0 A (D) 3.0 A 32. A potential difference of 12 V causes 0.35 C of electric charge to pass through a resistor in 2.6 s. How much power does the resistor dissipate? (A) 1.6 W (B) 4.2 W (C) 11 W (D) 89 W 8 3% 52 (d) A high voltage power line has a resistivity of m, a diameter of 2.2 cm and carries a current of 50.0 A. If a bird lands on the power line, calculate the distance between its feet if 5 the potential difference across its body is V. Page 7

8 5% 52.(e) Given the circuit in the diagram below, calculate: (i) the voltage drop across R1. (ii) the current through R2. June What is current a measure of? (A) amount of energy given to a charged object (C) number of charges stored in a cell (B) charge passing a point in a given time (D) resistance to the flow of particles 30. A piece of copper wire, with a resistance of 1000, is cut into five equal lengths that are then connected in parallel. What is the total resistance of this combination? (A) 40 (B) 200 (C) 1000 (D) What is the total resistance of the circuit below? (A) 9.6 (B) 12.0 (C) 16.1 (D) In the circuit below, the current through the 40.0 resistor is 90.0 ma. What is the current through the 60.0 resistor? (A) 30.0 ma (C) 60.0 ma (B) 45.0 ma (D) 90.0 ma Page 8

9 33. If a 2.0, 4.0, and 6.0 resistor are connected in series with a 24 V battery, what is the potential difference across the 2.0 resistor? (A) 4.0 V (B) 8.0 V (C) 12 V (D) 24 V 5% 52.(c) Given the circuit in the diagram below, calculate: (i) the current through the 5.00 resistor. (ii) the resistance of R. (iii) the potential difference across the battery. 3% 52 (d) A soldering iron of resistance 576 is connected to a 120 V circuit. Calculate the cost to operate the soldering iron 8.0 hours a day for 21 days, if energy costs $0.080/kW h. August By which process does a solar calculator get its energy? (A) photo electricity (B) piezo-electricity (C) thermoelectricity (D) voltaic cell 27. Wire A has a resistance of 12 S. Wire B, of the same material, is twice as long and has half the cross-sectional radius of wire A. What is the resistance of wire B? (A) 1.5 (B) 12 (C) 48 (D) What is the value of I in the circuit junction below? (A) 6 A (B) 10 A (C) 14 A (D) 30 A Page 9

10 29. Who proposed that around any closed path, the sum of the voltage rises is equal to the sum of the voltage drops? (A) Coulomb (B) Kirchoff (C) Ohm (D) Voltaire 30. How many electrons are transferred in a 10.0 A current that runs for 3.0 s? (A) (B) (C) (D) If a copper wire was connected across points X and Y in the circuit below, what would be the current through the bulb and what would happen to the brightness of bulb? Current (A) Brightness (A) 0.64 dimmer (B) 0.64 brighter (C) 1.1 dimmer (D) 1.1 brighter 32. If four 20 resistors are connected in parallel, what is the equivalent resistance? (A) 5 (B) 10 (C) 20 (D) If a W hair dryer has a 10.0 resistance, how much current will it draw? (A) A (B) 11 A (C) 12 A (D) 120 A 34. If a 2.0 kw heater operates for 10.0 hours, what is the cost of operating the heater if the rate is $0.11/kWh? (A) $2.20 (B) $0.22 (C) $1.10 (D) $ (b) For the circuit shown in the diagram below, calculate: 2% (i) the total resistance; 4% (ii) the current through each resistor; Page 10

11 4% (f) A kitchen has two 120 W light bulbs, a 450 W coffee maker, and a 1280 W deep fryer operating on the same 120 V circuit at the same time. The circuit is protected by a 20.0 A fuse. What will happen if a 1200 W dishwasher is switched on within the same circuit? Use calculations to justify your answer. June If a series circuit contains two 15 light bulbs, three 25 light bulbs, and a 24 V battery, how much current passes through each bulb? (A) 0.15 A (B) 0.23 A (C) 0.60 A (D) 1.7 A 28. Which best represents the relationship between resistance, R, and cross-sectional area, A, of copper wire? (A) (B) (C) (D) 29. What are the readings of V1 and V2 in the circuit below? V1 (volts) V2 (volts) (A) 2 4 (B) 4 2 (C) 3 3 (D) A string of 20 identical lights is connected in series across a 120 V source, and each light consumes 2.4 W. What is the resistance of each bulb? (A) 6.0 (B) 15 (C) 48 (D) 120 Page 11

12 June % 52.(d) For the circuit shown in the diagram below, calculate: (i) the voltage across the 6.0 resistor; (ii) the current through the 5.0 resistor; (iii) the power dissipated in the 2.0 resistor. August % 52. (c) For the circuit below, calculate: (i) the total resistance; (ii) the current through the 25 resistor; Page 12

13 3% 52.(d) A power supply is connected to a heating element in the diagram below. (i) Calculate the current flowing from the element. 20 (ii) If a total of electrons pass any point in the heating element circuit in 40 s, calculate the amount of power dissipated in the circuit. June % 52.(d) Use the circuit below to answer questions (i) and (ii). (i) What is the total resistance of the circuit? (ii) What is the current through each resistor in the circuit? Page 13

14 August % (c) Complete the table below for the given circuit. Show all workings in the space provided below the circuit diagram. June (b) Refer to the circuit diagram below to complete the questions that follow. For this circuit diagram, calculate: 3% (i) total current: 2% (ii) voltage drop across R2: 1% (iii) power dissipated by the parallel section: Page 14

15 Page 15