Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 579 · 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.🧩 Which component turns a fan or wheels? (a) motor (b) fuse (c) diode (d) capacitor
2. 2.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
3. 3.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) zero (d) smaller
4. 4.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the pipe colour (d) the flow of water
5. 5.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
6. 6.🔺 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
7. 7.🌈 A resistor has the colour bands green, black, yellow. What is its value in kilo-ohms (kΩ)? =
8. 8.🌈 A resistor has the colour bands green, green, black. What is its value (in ohms)?
9. 9.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
10. 10.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.Which of these is measured in amperes (A)? (a) resistance (b) the push of a cell (c) voltage (d) the flow of charge
12. 12.🧮 A 20 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
13. 13.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) the flow of water (c) a bigger tank (d) a narrow pipe
14. 14.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R
15. 15.💡 An LED is joined to a 9 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) does not light (b) lights up (c) may burn out
16. 16.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🔍 Which is the odd one out? (a) use old filament bulbs (b) run fans in empty rooms (c) leave the TV on standby (d) switch off empty rooms
18. 18.True or false: the voltmeter is joined across a part. (a) True (b) False
19. 19.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) more than either one (d) their sum
20. 20.🔺 A current of 3 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.🔺 An 8.25 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
22. 22.🌈 In the resistor colour code, which number does yellow stand for?
23. 23.🔍 Which is the odd one out? (a) leave fridge door open (b) unplug idle chargers (c) use LED lamps (d) use daylight to read
24. 24.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) store charge briefly (d) measure heat
25. 25.Which of these saves electricity? (a) leave the TV on standby (b) switch off empty rooms (c) use old filament bulbs (d) iron one shirt at a time
26. 26.🔍 Which is the odd one out? (a) unplug idle chargers (b) run fans in empty rooms (c) switch off empty rooms (d) use daylight to read
27. 27.True or false: to run fans in empty rooms saves electricity. (a) False (b) True
28. 28.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
30. 30.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
31. 31.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
32. 32.📏 Which unit measures power? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
33. 33.🔺 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
34. 34.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
35. 35.🌈 A resistor has the colour bands red, blue, orange. What is its value in kilo-ohms (kΩ)? =
36. 36.🧮 A 1.5 V battery is joined to 3 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
37. 37.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
38. 38.📏 How many kilowatts (kW) is 1150 W? =
39. 39.📏 How many ohms (Ω) is 8.9 kΩ?
40. 40.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?

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