Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 420 · 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 band is read first on a resistor? (a) the widest gap (b) any band (c) the gold band (d) the one nearest an end
2. 2.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
3. 3.🧩 Which component boosts a small signal? (a) potentiometer (b) capacitor (c) thermistor (d) transistor
4. 4.True or false: a transistor boosts a small signal. (a) True (b) False
5. 5.🌈 A resistor has the colour bands blue, blue, red. What is its value in kilo-ohms (kΩ)? =
6. 6.🌈 A resistor has the colour bands yellow, brown, red. What is its value (in ohms)?
7. 7.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
8. 8.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) a bigger tank (c) a narrow pipe (d) the flow of water
9. 9.True or false: the voltmeter is joined in series. (a) True (b) False
10. 10.🧮 Resistors of 20 Ω, 20 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
13. 13.True or false: the ammeter is joined in series. (a) False (b) True
14. 14.🔺 A current of 1.5 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
16. 16.🧮 Resistors of 33 Ω, 10 Ω, 330 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
17. 17.🔺 A 30 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
18. 18.🧩 A capacitor in a circuit can … (a) spin a wheel (b) measure heat (c) make light (d) store charge briefly
19. 19.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) an LED lamp (c) a filament bulb (d) a candle
20. 20.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
21. 21.🌈 A resistor has the colour bands white, green, red. What is its value in kilo-ohms (kΩ)? =
22. 22.🧩 Which component stores a little charge? (a) transistor (b) potentiometer (c) fuse (d) capacitor
23. 23.🔺 A 5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
24. 24.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
25. 25.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
26. 26.🌈 A resistor has the colour bands brown, white, red. What is its value (in ohms)?
27. 27.🌈 A resistor has the colour bands blue, white, yellow. What is its value in kilo-ohms (kΩ)? =
28. 28.🌈 In the resistor colour code, which number does black stand for?
29. 29.True or false: resistance is measured in volts (V). (a) True (b) False
30. 30.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
32. 32.📏 How many kilowatts (kW) is 2550 W? =
33. 33.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
35. 35.🔺 A 6 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
36. 36.🔺 A current of 0.2 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
38. 38.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
39. 39.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🧩 Which component makes things spin? (a) capacitor (b) motor (c) buzzer (d) resistor

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