Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 404 · 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.True or false: to use old filament bulbs saves electricity. (a) False (b) True
2. 2.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) store charge briefly (d) measure heat
3. 3.⚡ A 1 W device works on 5 V. What current does it take (in amperes)? =
4. 4.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
5. 5.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
6. 6.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
7. 7.Which of these saves electricity? (a) leave the TV on standby (b) use daylight to read (c) leave fridge door open (d) use old filament bulbs
8. 8.🧮 Resistors of 47 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
9. 9.🌈 A resistor has the colour bands yellow, grey, orange. What is its value in kilo-ohms (kΩ)? =
10. 10.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) any band (d) the gold band
12. 12.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
13. 13.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
14. 14.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🌈 A resistor has the colour bands blue, grey, orange. What is its value in kilo-ohms (kΩ)? =
16. 16.📏 How many watts (W) is 4.5 kW?
17. 17.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero
18. 18.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
19. 19.🧮 A 20 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
20. 20.📏 How many milliamperes (mA) is 0.05 A?
21. 21.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) zero (d) stay the same
22. 22.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
23. 23.True or false: the push of a cell is measured in amperes (A). (a) False (b) True
24. 24.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 60 (c) 10 (d) 1000
25. 25.🔺 A current of 0.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
26. 26.Which of these is measured in ohms (Ω)? (a) energy used each second (b) power (c) the push of a cell (d) how much a part resists
27. 27.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I
28. 28.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
29. 29.Which of these saves electricity? (a) run fans in empty rooms (b) use old filament bulbs (c) leave fridge door open (d) set the AC to 24 °C
30. 30.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
31. 31.Which of these wastes electricity? (a) switch off empty rooms (b) leave the TV on standby (c) set the AC to 24 °C (d) use daylight to read
32. 32.🌈 A resistor has the colour bands brown, green, red. What is its value in kilo-ohms (kΩ)? =
33. 33.💡 An LED is joined to a 6 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
34. 34.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
35. 35.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a resistor (d) a motor
36. 36.💡 A red LED uses 2 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
37. 37.📏 How many amperes (A) is 1090 mA? =
38. 38.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to limit the current (d) to change its colour
39. 39.🧮 A 22 V battery is joined to 10 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
40. 40.True or false: resistance is measured in ohms (Ω). (a) False (b) True

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