Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 71 · 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.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the water tank lid (c) the pipe colour (d) the tap handle
2. 2.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 10 (c) 60 (d) 100
3. 3.🧩 Which component turns a fan or wheels? (a) transistor (b) diode (c) thermistor (d) motor
4. 4.True or false: the voltmeter measures voltage. (a) True (b) False
5. 5.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a filament bulb (c) an oil lamp (d) a candle
6. 6.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
7. 7.💡 An LED is joined to a 6 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) does not light (c) may burn out
8. 8.🧮 Resistors of 68 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
9. 9.💡 What does LED stand for? (a) light energy dial (b) light-emitting diode (c) large electric dial (d) low energy device
10. 10.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
11. 11.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) gets smaller (d) stays the same
12. 12.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🔺 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
14. 14.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
15. 15.🔺 A 20 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
16. 16.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
17. 17.Which of these is measured in amperes (A)? (a) voltage (b) resistance (c) the push of a cell (d) current
18. 18.🌈 A resistor has the colour bands violet, orange, orange. What is its value (in ohms)?
19. 19.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
20. 20.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V + I (d) R = V × I
21. 21.🧮 Resistors of 100 Ω, 20 Ω, 50 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
22. 22.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
23. 23.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 100 (d) 1000
25. 25.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
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.True or false: a fuse senses how bright it is. (a) True (b) False
28. 28.🧮 A 5 V battery is joined to 2 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
29. 29.Which of these saves electricity? (a) set the AC to 24 °C (b) leave the TV on standby (c) use old filament bulbs (d) run fans in empty rooms
30. 30.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
31. 31.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
32. 32.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
33. 33.📏 Which unit measures resistance? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
34. 34.True or false: to unplug idle chargers saves electricity. (a) True (b) False
35. 35.🧮 Resistors of 47 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
36. 36.🧮 Resistors of 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I
38. 38.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🌈 A resistor has the colour bands grey, red, orange. What is its value (in ohms)?
40. 40.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) store charge briefly (d) measure heat

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