Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 961 · 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.🌈 In the resistor colour code, which number does orange stand for?
2. 2.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
3. 3.🧩 Which component senses how hot it is? (a) transistor (b) fuse (c) LDR (d) thermistor
4. 4.What does a motor do? (a) senses how bright it is (b) limits the current (c) has coloured bands (d) makes things spin
5. 5.🌈 In the resistor colour code, which number does red stand for?
6. 6.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
7. 7.📏 Which unit measures resistance? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9200 Ω resistor? (a) white-red-red (b) white-red-orange (c) red-white-red (d) white-red-brown
9. 9.🔺 A current of 3 A flows when 36 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
11. 11.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
12. 12.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) light energy dial (d) low energy device
13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets bigger (d) gets smaller
14. 14.🔺 A current of 3 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🔺 A current of 0.1 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 27000 Ω resistor? (a) red-violet-red (b) red-violet-orange (c) violet-red-orange (d) red-violet-yellow
17. 17.📏 How many amperes (A) is 2870 mA? =
18. 18.🌈 A resistor has the colour bands violet, black, orange. What is its value (in ohms)?
19. 19.🧮 A 4 V battery is joined to 6 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
20. 20.🌈 A resistor has the colour bands orange, red, orange. What is its value in kilo-ohms (kΩ)? =
21. 21.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
22. 22.True or false: a resistor has coloured bands. (a) True (b) False
23. 23.True or false: the ammeter is joined in series. (a) True (b) False
24. 24.🧮 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
25. 25.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
26. 26.📏 How many milliamperes (mA) is 0.32 A?
27. 27.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
28. 28.🌈 In the resistor colour code, which number does yellow stand for?
29. 29.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
30. 30.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
31. 31.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
32. 32.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an LED lamp (d) an oil lamp
33. 33.🧮 A 22 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
34. 34.🌈 A resistor has the colour bands violet, orange, red. What is its value (in ohms)?
35. 35.True or false: to iron one shirt at a time wastes electricity. (a) False (b) True
36. 36.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
37. 37.True or false: a capacitor boosts a small signal. (a) False (b) True
38. 38.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
39. 39.🔺 A current of 0.25 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
40. 40.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)

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