Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 721 · 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.What does a transistor do? (a) makes a beeping sound (b) beeps for an alarm (c) has coloured bands (d) boosts a small signal
2. 2.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
3. 3.🧾 A 200 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
4. 4.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
5. 5.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.🔍 Which is the odd one out? (a) use LED lamps (b) close the fridge quickly (c) unplug idle chargers (d) iron one shirt at a time
7. 7.True or false: resistance is measured in watts (W). (a) True (b) False
8. 8.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
9. 9.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) make light (d) measure heat
10. 10.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
11. 11.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
12. 12.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
13. 13.📏 Which unit measures resistance? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
14. 14.🌈 A resistor has the colour bands white, white, red. What is its value in kilo-ohms (kΩ)? =
15. 15.🌈 A resistor has the colour bands red, orange, orange. What is its value in kilo-ohms (kΩ)? =
16. 16.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
17. 17.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
18. 18.🌈 A resistor has the colour bands white, grey, red. What is its value in kilo-ohms (kΩ)? =
19. 19.🌈 In the resistor colour code, which number does black stand for?
20. 20.🧮 A 6 V battery is joined to 6 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
21. 21.True or false: current is measured in amperes (A). (a) False (b) True
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 380 Ω resistor? (a) orange-grey-red (b) orange-grey-brown (c) grey-orange-brown (d) orange-grey-black
23. 23.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
24. 24.True or false: a diode blows if current is high. (a) False (b) True
25. 25.🧩 Which component limits the current? (a) resistor (b) LDR (c) diode (d) capacitor
26. 26.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
28. 28.🧮 A 2.8 V battery is joined to 6 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
29. 29.Which of these saves electricity? (a) use daylight to read (b) run fans in empty rooms (c) use old filament bulbs (d) iron one shirt at a time
30. 30.What does an LDR do? (a) boosts a small signal (b) senses how bright it is (c) lets current go one way (d) is a resistance knob
31. 31.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
32. 32.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
33. 33.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.🧮 Resistors of 330 Ω, 20 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
35. 35.🧮 A 2 V battery is joined to 8 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
36. 36.💡 What does LED stand for? (a) light energy dial (b) low energy device (c) large electric dial (d) light-emitting diode
37. 37.🔍 Which is the odd one out? (a) use LED lamps (b) switch off empty rooms (c) leave the TV on standby (d) set the AC to 24 °C
38. 38.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
39. 39.🧮 A 3.5 V battery is joined to 12 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
40. 40.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =

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