Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 566 · 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.🧮 Resistors of 50 Ω, 20 Ω, 20 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
2. 2.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = R ÷ I (d) V = I × R
3. 3.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🧮 Resistors of 68 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) measure heat (d) make light
7. 7.True or false: voltage is measured in amperes (A). (a) False (b) True
8. 8.💡 What does LED stand for? (a) low energy device (b) light-emitting diode (c) light energy dial (d) large electric dial
9. 9.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
10. 10.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
11. 11.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
12. 12.🔺 A current of 25 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
14. 14.Which of these saves electricity? (a) leave the TV on standby (b) switch off empty rooms (c) iron one shirt at a time (d) use old filament bulbs
15. 15.True or false: to leave fridge door open saves electricity. (a) False (b) True
16. 16.🧮 A 10 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
17. 17.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
19. 19.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
20. 20.📏 How many ohms (Ω) is 8 kΩ?
21. 21.💡 A red LED uses 2 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
22. 22.🧮 Resistors of 68 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
23. 23.🧩 Which component senses how hot it is? (a) fuse (b) potentiometer (c) buzzer (d) thermistor
24. 24.🌈 In the resistor colour code, which number does grey stand for?
25. 25.True or false: to switch off empty rooms wastes electricity. (a) False (b) True
26. 26.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
27. 27.🔺 A current of 1 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.🧩 Which component limits the current? (a) transistor (b) buzzer (c) resistor (d) diode
30. 30.🔺 A current of 1.5 A flows when 22.5 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) zero (d) stay the same
32. 32.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
33. 33.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
34. 34.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
35. 35.What does a buzzer do? (a) lets current go one way (b) senses how hot it is (c) stores a little charge (d) beeps for an alarm
36. 36.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets smaller (d) gets bigger
37. 37.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
38. 38.🔺 A current of 1 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
40. 40.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the tap handle (c) the water pressure (d) the pipe colour

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