Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 689 · 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.🔍 Which is the odd one out? (a) use daylight to read (b) unplug idle chargers (c) use LED lamps (d) run fans in empty rooms
2. 2.🧮 A 0.9 V battery is joined to 4 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
3. 3.💡 What happens if an LED is put in backwards? (a) it does not light (b) it lights brighter (c) it makes a sound (d) it changes colour
4. 4.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
5. 5.⚡ A 1.5 W device works on 6 V. What current does it take (in amperes)? =
6. 6.True or false: voltage is measured in volts (V). (a) False (b) True
7. 7.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
8. 8.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
9. 9.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
10. 10.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
11. 11.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) an LED lamp (d) a filament bulb
12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
13. 13.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the flow of water (d) the pipe colour
14. 14.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
15. 15.🧮 A 330 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
16. 16.Which of these wastes electricity? (a) leave the TV on standby (b) switch off empty rooms (c) use LED lamps (d) unplug idle chargers
17. 17.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
18. 18.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
19. 19.📏 How many amperes (A) is 2230 mA? =
20. 20.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = R ÷ I (c) V = I × R (d) V = I ÷ R
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 75 Ω resistor? (a) grey-green-black (b) violet-green-brown (c) green-violet-black (d) violet-green-black
23. 23.🌈 A resistor has the colour bands red, black, black. What is its value (in ohms)?
24. 24.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
25. 25.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
26. 26.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
27. 27.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
28. 28.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 watt (d) 1 kilowatt-hour (kWh)
29. 29.🔺 A current of 3 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
31. 31.True or false: the voltmeter is joined in series. (a) True (b) False
32. 32.🧮 Resistors of 100 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
33. 33.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V + R (c) I = V ÷ R (d) I = V × R
34. 34.📏 How many ohms (Ω) is 7.2 kΩ?
35. 35.True or false: how much a part resists is measured in watts (W). (a) True (b) False
36. 36.Which of these saves electricity? (a) leave fridge door open (b) leave the TV on standby (c) use old filament bulbs (d) set the AC to 24 °C
37. 37.🔺 A current of 0.2 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) stays the same (d) gets bigger
39. 39.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
40. 40.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?

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