Review for formula, circuit and resistance test

Transcription

1 Review for formula, circuit and resistance test 1. Fill in the table giving the symbol and unit(s) for each. Current intensity Potential difference Voltage Resistance Power Energy Time 2. Give the formula and then the triangles for each. Potential difference Power Energy 1 Energy 2 3. Give the conversions W to kw J to kwh sec to hrs J to kj sec to min min to sec hrs to sec 4. How much power did an electric lawn mower use if it used J of energy in the 50 minutes it took to mow the lawn? 5. How much time was a fish tank on when it needed 0.5 A, 100 V and J of energy? 6. A man used the computer for 7 hours and used 500 W of power. How much energy did it take to use the computer for seven hours? 7. What is the potential difference of a light bulb when it uses a 200 Ω resistor and 0.4 A? 8. A radio is on for 150 minutes and has 450 W of power. What is the energy in kwh? 9. A toaster takes 300 seconds to toast a piece of bread. If it uses 400 W of power how much energy will be used in J?

2 10. If a TV used J of work and 90 W of power. How many hours did you watch TV for? 11. An electric radiator with a resistance of 40 is connected to a 220 V circuit for 1.00 hour. What is the power of this radiator? A) 1.21 kw B) 5.50 kw C) 19.8 kw D) kw 12. On an electric heater are written the following specifications : 110 V W. What is the resistance of this heater? A) 61 B) 22 C) 5 D) While having breakfast, you notice the following information on the specification plate of the toaster: You also note that this toaster toasts the bread in 1.5 minutes. 120 V 6 A 60 Hz What quantity of electrical energy is consumed by the toaster's element to toast the bread? A) 720 J B) J C) J D) J 14. Calculate the resistance value in the circuit below. 15. During a lab experiment, you have to assemble a circuit based on the following information: The circuit is composed of a 6.0-V battery connected to a 10-Ω resistor. It includes an ammeter and a voltmeter connected to the resistor terminals. a) Draw the circuit diagram, including the measuring instruments. b) What values will the ammeter and voltmeter display? c) How much energy will the resistor release in one minute s work?

3 16. Draw a series and parallel circuit, each with two resistors. Include a switch and a fuse for the controlling the whole circuit. Series Parallel 17. Draw a circuit where current intensity has 4 possible pathways. Use the specifics below when drawing the circuit - Place a voltmeter that measures the potential difference coming from the power source, use Vt as your symbol. - Place a voltmeter that measures the potential difference across resistor R 2, use V 2 as your symbol. - Place an ammeter that measures the current intensity from the power source, use At as your symbol. - Place an ammeter that measures the current intensity through resistor R 3, use A 3 as your symbol. - Place an ammeter that measures the current intensity through resistor R 3 and resistor R 4, use A 4 as your symbol. - Place a switch that will cause the whole circuit to stop working when it is open. - Place a switch that will cause resistor R 1 to stop working when it is opened. - Place a switch that will cause resistors R 2, R 3, and R 4 to stop working when it is opened. - Place a fuse to control the whole circuit - Place a switch to control resistor Look at the electrical circuit. a) Determine if each circuit is an open or closed one. b) Determine if the light bulb will be on for each circuit. Circuit A Circuit B 19. In the lab, you have been given the following materials: a battery, three lamps, two switches and a fuse. You must assemble a circuit containing the battery, one switch and the three lamps. The lamps are to be connected in parallel, and they must all turn on at the same time and give off the same intensity of light. The fuse must be installed so that the total current intensity does not exceed 2.4 A.

4 a) Draw the diagram for this electrical circuit. b) What would happen if the current in the circuit in question a) were to exceed 2.4 A? 20. Fuses and breakers perform the same function in electrical circuits. What is this function called? 21. When a lamp is switched off, is the electrical circuit to the light bulb open or closed? Explain your answer. 22. When you go to a friend s house and ring the doorbell, an electrical circuit is activated, and the doorbell rings. a) When you press the button for the doorbell, you close an electrical circuit. Which function does the push button perform in the circuit? b) The doorbell is covered in plastic. Why? Which function does this small round plastic cover perform? 23. Four electric circuit diagrams are given below. You wish to measure the potential difference across the terminals of resistor R2. Which diagrams show a correctly connected voltmeter? A) 1 and 3 B) 2 and 4 C) 1 and 2 D) 2 and The following electric circuit consists of a power supply, VT, connected to three resistors (R1, R2 andr3). Which of the following circuit diagrams shows the correct connection for an ammeter A that measures the current flowing through resistor R1?

5 25. An electrical circuit consists of a power source, two switches (S 1 and S 2) and two light bulbs (L 1 and L 2). The following table shows what happens to both light bulbs: Switch Light Bulb S 1 S 2 L 1 L 2 open open out out closed open bright out Which of the following circuit diagrams illustrates the results shown in the table above? A) C) B) D) 26. The following table gives the characteristics of four electrical conductors. Conductor Length Diameter Temperature F 1 1 m 2 mm -20 C F 2 3 m 2 mm 50 C F 3 1 m 1 mm 50 C F 4 3 m 1 mm -20 C Which is the best electrical conductor? A) F 1 B) F 2 C) F 3 D) F 4

6 27. A circuit consists of a power supply, a light bulb and two terminals that can be connected to a rod. The copper rods illustrated below are inserted into the circuit one at a time. The rods are the same temperature, but they have different dimensions. Which rod will offer the least resistance to the flow of electric current? A) rod 1 B) rod 2 C) rod 3 D) rod Use the results to answer the questions. Voltage (V) Current (A) Draw a resistance graph Find the resistance 29. The following graph describes the behavior of three resistors subjected to different voltages. Which is the resistor would you use as the best conductor? Justify your answer using calculations. V (V) IV