Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 88 · 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.🔺 A current of 0.25 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.🧩 Which component has coloured bands? (a) LED (b) diode (c) fuse (d) resistor
3. 3.🧮 Resistors of 150 Ω, 470 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
4. 4.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
5. 5.⚡ A 2.5 W device works on 5 V. What current does it take (in amperes)? =
6. 6.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🌈 A resistor has the colour bands yellow, green, red. What is its value (in ohms)?
8. 8.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
9. 9.True or false: power is measured in ohms (Ω). (a) False (b) True
10. 10.🧮 Resistors of 10 Ω, 68 Ω, 220 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.🔍 Which is the odd one out? (a) leave fridge door open (b) unplug idle chargers (c) use LED lamps (d) use daylight to read
12. 12.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 10 (c) 1000 (d) 100
13. 13.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
14. 14.🔺 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
15. 15.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
16. 16.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
17. 17.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) the widest gap (d) any band
18. 18.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) large electric dial (d) low energy device
19. 19.🔺 A current of 1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
20. 20.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
21. 21.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 81000 Ω resistor? (a) grey-brown-yellow (b) brown-grey-orange (c) grey-brown-red (d) grey-brown-orange
23. 23.Which of these wastes electricity? (a) leave the TV on standby (b) close the fridge quickly (c) use daylight to read (d) unplug idle chargers
24. 24.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = I ÷ V (d) R = V + I
25. 25.🧮 A 1.2 V battery is joined to 4 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
26. 26.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
27. 27.⚡ A 3 W device works on 3 V. What current does it take (in amperes)? =
28. 28.🌈 In the resistor colour code, which number does white stand for?
29. 29.📏 How many amperes (A) is 300 mA? =
30. 30.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🧮 Resistors of 22 Ω, 68 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
32. 32.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
33. 33.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
34. 34.🔺 A current of 0.1 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an oil lamp (d) an LED lamp
36. 36.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = V ÷ I (d) P = I ÷ V
37. 37.🌈 In the resistor colour code, which number does orange stand for?
38. 38.🌈 A resistor has the colour bands white, red, orange. What is its value (in ohms)?
39. 39.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) store charge briefly (d) spin a wheel
40. 40.Which of these is measured in watts (W)? (a) resistance (b) power (c) the push of a cell (d) how much a part resists

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