Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 458 · 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.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
2. 2.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) the size of a cell (d) energy used each second
3. 3.🧮 A 1 V battery is joined to 4 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
4. 4.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
5. 5.⚡ A device works on 5 V and takes 0.5 A. What is its power (in watts)? =
6. 6.Which of these is measured in volts (V)? (a) energy used each second (b) current (c) power (d) voltage
7. 7.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
8. 8.🔺 A 25 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
9. 9.⚡ A 2.5 W device works on 5 V. What current does it take (in amperes)? =
10. 10.🧮 Resistors of 150 Ω, 47 Ω, 330 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.🌈 A resistor has the colour bands yellow, black, black. What is its value (in ohms)?
12. 12.🌈 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
13. 13.🌈 A resistor has the colour bands grey, yellow, brown. What is its value (in ohms)?
14. 14.🧮 Resistors of 33 Ω, 100 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
15. 15.🧮 Resistors of 100 Ω, 470 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
16. 16.⚡ A 36 W device works on 24 V. What current does it take (in amperes)? =
17. 17.True or false: voltage is measured in amperes (A). (a) True (b) False
18. 18.🔺 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
19. 19.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V + R (c) I = V × R (d) I = R ÷ V
20. 20.🌈 In the resistor colour code, which number does brown stand for?
21. 21.🔺 A current of 2.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
22. 22.⚡ A device works on 24 V and takes 1.5 A. What is its power (in watts)? =
23. 23.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
24. 24.💡 What does LED stand for? (a) light energy dial (b) low energy device (c) large electric dial (d) light-emitting diode
25. 25.🔺 A current of 0.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🔺 A 15 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
27. 27.🌈 A resistor has the colour bands violet, brown, red. What is its value (in ohms)?
28. 28.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
29. 29.True or false: the voltmeter is joined across a part. (a) False (b) True
30. 30.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.⚡ A 3 W device works on 3 V. What current does it take (in amperes)? =
32. 32.🔺 An 8.25 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
33. 33.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) spin a wheel (d) measure heat
34. 34.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
35. 35.🧮 Resistors of 150 Ω, 470 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
36. 36.⚡ A 4.8 W device works on 24 V. What current does it take (in amperes)? =
37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 74000 Ω resistor? (a) yellow-violet-orange (b) violet-yellow-yellow (c) violet-yellow-red (d) violet-yellow-orange
38. 38.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
39. 39.True or false: a capacitor boosts a small signal. (a) False (b) True
40. 40.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?

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