Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 575 · 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.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
2. 2.💡 An LED is joined to a 9 V battery through a 220 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
3. 3.🌈 In the resistor colour code, which number does green stand for?
4. 4.🧩 Which component boosts a small signal? (a) capacitor (b) diode (c) buzzer (d) transistor
5. 5.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
6. 6.True or false: the voltmeter is joined across a part. (a) True (b) False
7. 7.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V + R (d) I = V × R
9. 9.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
10. 10.🧮 Resistors of 68 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
12. 12.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.🧾 A 200 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
14. 14.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
16. 16.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
18. 18.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
19. 19.🔺 A 36 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
20. 20.Which of these is measured in volts (V)? (a) current (b) voltage (c) energy used each second (d) resistance
21. 21.🧩 Which component has coloured bands? (a) potentiometer (b) buzzer (c) motor (d) resistor
22. 22.🔺 A 3 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
23. 23.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🧮 Resistors of 150 Ω, 100 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
25. 25.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
26. 26.📏 Which unit measures voltage? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
27. 27.⚡ A 4.5 W device works on 3 V. What current does it take (in amperes)? =
28. 28.📏 Which unit measures resistance? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
29. 29.📏 How many amperes (A) is 30 mA? =
30. 30.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
31. 31.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.🧮 Resistors of 150 Ω, 330 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
33. 33.🌈 A resistor has the colour bands blue, white, yellow. What is its value in kilo-ohms (kΩ)? =
34. 34.🔺 A 5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
35. 35.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I ÷ R (d) V = I + R
36. 36.🔍 Which is the odd one out? (a) leave the TV on standby (b) run fans in empty rooms (c) iron one shirt at a time (d) set the AC to 24 °C
37. 37.True or false: to close the fridge quickly wastes electricity. (a) False (b) True
38. 38.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
39. 39.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
40. 40.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)

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