Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 394 · 40 questions

Remember (Find the topic, use the formula): Find the topic and the formula: V = I × R, I = V ÷ R, R = V ÷ I, P = V × I, units = W × h ÷ 1000. Change mA to A and kΩ to Ω before using a formula. Check: put your answer back into the formula.

1. 1.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V × I (c) R = V ÷ I (d) R = I ÷ V
2. 2.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🧩 Which component makes a beeping sound? (a) capacitor (b) diode (c) buzzer (d) potentiometer
4. 4.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
5. 5.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.🧮 A 2.2 V battery is joined to 3 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
7. 7.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) gets smaller (d) stays the same
8. 8.💡 An LED is joined to a 5 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) may burn out (c) does not light
9. 9.📏 Which unit measures current? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
10. 10.What does a thermistor do? (a) stores a little charge (b) senses how hot it is (c) boosts a small signal (d) lets current go one way
11. 11.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
12. 12.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
13. 13.True or false: the voltmeter is joined in series. (a) True (b) False
14. 14.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
15. 15.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
16. 16.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) an LED (d) a resistor
17. 17.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
18. 18.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
19. 19.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
20. 20.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
21. 21.What does a transistor do? (a) senses how bright it is (b) boosts a small signal (c) limits the current (d) is a resistance knob
22. 22.🧮 A 0.8 V battery is joined to 6 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
23. 23.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
24. 24.True or false: to iron one shirt at a time saves electricity. (a) False (b) True
25. 25.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
26. 26.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
27. 27.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
28. 28.📏 How many kilowatts (kW) is 4400 W? =
29. 29.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
30. 30.Which of these wastes electricity? (a) unplug idle chargers (b) leave the TV on standby (c) switch off empty rooms (d) use LED lamps
31. 31.💡 What does LED stand for? (a) low energy device (b) light-emitting diode (c) light energy dial (d) large electric dial
32. 32.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
33. 33.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I
34. 34.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = I ÷ V (d) P = V + I
35. 35.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
36. 36.🔺 A 15 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
37. 37.📏 How many kilowatts (kW) is 1250 W? =
38. 38.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
39. 39.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it does not light (c) it makes a sound (d) it changes colour
40. 40.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 50 % (d) 0 %

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