Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 462 · 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 resistor has the colour bands orange, blue, brown. What is its value (in ohms)?
2. 2.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
3. 3.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) less than either one (d) their sum
4. 4.🔺 An 8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
5. 5.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
6. 6.🧾 A 50 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
7. 7.🧮 A 3 V battery is joined to 2 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
8. 8.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
9. 9.📏 How many watts (W) is 0.1 kW?
10. 10.True or false: the voltmeter is joined in series. (a) True (b) False
11. 11.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 ampere
12. 12.🔺 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
13. 13.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 50 % (d) 0 %
14. 14.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a resistor (d) a motor
15. 15.🔍 Which is the odd one out? (a) switch off empty rooms (b) close the fridge quickly (c) use old filament bulbs (d) use daylight to read
16. 16.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the gold band (d) the widest gap
17. 17.📏 Which unit measures power? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
18. 18.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
19. 19.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
20. 20.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
21. 21.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an LED lamp (d) an oil lamp
23. 23.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the size of a cell (d) the length of a wire
24. 24.🧮 A 2.4 V battery is joined to 8 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
25. 25.Which of these wastes electricity? (a) use daylight to read (b) use LED lamps (c) iron one shirt at a time (d) set the AC to 24 °C
26. 26.📏 Which unit measures voltage? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
27. 27.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = R ÷ V (d) I = V ÷ R
28. 28.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it makes a sound (d) it lights brighter
29. 29.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
30. 30.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) make light (d) measure heat
32. 32.📏 How many amperes (A) is 1830 mA? =
33. 33.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
34. 34.True or false: to use daylight to read wastes electricity. (a) False (b) True
35. 35.📏 How many kilowatts (kW) is 4000 W? =
36. 36.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
37. 37.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to change its colour (d) to limit the current
38. 38.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
39. 39.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
40. 40.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?

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