Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 353 · 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.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
2. 2.💡 An LED is joined to a 5 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) may burn out (c) lights up
3. 3.🔺 A current of 0.25 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
5. 5.🌈 A resistor has the colour bands orange, red, orange. What is its value (in ohms)?
6. 6.Which of these is measured in ohms (Ω)? (a) resistance (b) the flow of charge (c) voltage (d) current
7. 7.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
8. 8.📏 How many amperes (A) is 230 mA? =
9. 9.🧮 A 4.5 V battery is joined to 6 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
10. 10.🧮 Resistors of 47 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) a narrow pipe (c) the flow of water (d) the water pressure
12. 12.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
14. 14.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the one nearest an end (d) the gold band
15. 15.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
16. 16.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
17. 17.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
18. 18.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it makes a sound (d) it does not light
19. 19.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
20. 20.True or false: power is measured in watts (W). (a) False (b) True
21. 21.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a motor (d) a resistor
22. 22.🧮 A 100 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
23. 23.⚡ A device works on 24 V and takes 0.1 A. What is its power (in watts)? =
24. 24.📏 How many milliamperes (mA) is 1.62 A?
25. 25.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 ampere (c) 1 watt (d) 1 volt
26. 26.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
28. 28.🌈 A resistor has the colour bands violet, yellow, yellow. What is its value in kilo-ohms (kΩ)? =
29. 29.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) a narrow pipe (c) the flow of water (d) the water pressure
30. 30.💡 An LED is joined to a 9 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
31. 31.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) always zero (d) less than either one
32. 32.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
33. 33.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
34. 34.Which of these wastes electricity? (a) set the AC to 24 °C (b) unplug idle chargers (c) use LED lamps (d) iron one shirt at a time
35. 35.🔺 A 37.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
36. 36.🌈 A resistor has the colour bands blue, brown, brown. What is its value (in ohms)?
37. 37.📏 How many kilowatts (kW) is 3300 W? =
38. 38.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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