Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 570 · 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 4.8 W device works on 24 V. What current does it take (in amperes)? =
2. 2.🌈 A resistor has the colour bands white, red, orange. What is its value (in ohms)?
3. 3.🔺 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
4. 4.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I ÷ R (c) V = I + R (d) V = I × R
5. 5.🔺 A 1.2 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
6. 6.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
7. 7.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
8. 8.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
9. 9.🔍 Which is the odd one out? (a) run fans in empty rooms (b) unplug idle chargers (c) use old filament bulbs (d) leave the TV on standby
10. 10.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) low energy device (d) light-emitting diode
11. 11.📏 How many kilowatts (kW) is 2250 W? =
12. 12.🌈 A resistor has the colour bands grey, brown, red. What is its value in kilo-ohms (kΩ)? =
13. 13.Which of these wastes electricity? (a) switch off empty rooms (b) use daylight to read (c) leave fridge door open (d) close the fridge quickly
14. 14.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🧮 A 50 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)?
17. 17.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
18. 18.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets bigger (d) gets smaller
20. 20.Which of these wastes electricity? (a) use LED lamps (b) iron one shirt at a time (c) switch off empty rooms (d) unplug idle chargers
21. 21.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 watt (c) 1 kilowatt-hour (kWh) (d) 1 ampere
22. 22.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
23. 23.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
24. 24.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
25. 25.🧮 Resistors of 47 Ω, 470 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) less than either one (d) more than either one
28. 28.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🔺 A current of 3 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
31. 31.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
32. 32.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) does not light (c) may burn out
33. 33.True or false: a resistor has coloured bands. (a) False (b) True
34. 34.🔺 An 8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
35. 35.Which of these is measured in amperes (A)? (a) the push of a cell (b) voltage (c) current (d) how much a part resists
36. 36.🧩 Which component lets current go one way? (a) diode (b) fuse (c) thermistor (d) resistor
37. 37.Which of these saves electricity? (a) run fans in empty rooms (b) unplug idle chargers (c) iron one shirt at a time (d) use old filament bulbs
38. 38.🧮 Resistors of 150 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
39. 39.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?

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