Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 600 · 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.🌈 A resistor has the colour bands brown, white, yellow. What is its value in kilo-ohms (kΩ)? =
2. 2.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a resistor (d) a buzzer
3. 3.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
4. 4.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to make it brighter (d) to change its colour
5. 5.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
6. 6.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 86 Ω resistor? (a) grey-blue-brown (b) grey-blue-black (c) blue-grey-black (d) white-blue-black
7. 7.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
8. 8.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.🌈 A resistor has the colour bands red, black, black. What is its value (in ohms)?
10. 10.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
11. 11.🧮 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
12. 12.📏 Which unit measures voltage? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
13. 13.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
14. 14.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
15. 15.🧮 A 150 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
16. 16.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
17. 17.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
18. 18.🌈 A resistor has the colour bands brown, yellow, orange. What is its value in kilo-ohms (kΩ)? =
19. 19.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
20. 20.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
22. 22.🔺 A 6 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
23. 23.🧩 Which component glows using little power? (a) resistor (b) LED (c) capacitor (d) LDR
24. 24.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) becomes zero (d) gets bigger
26. 26.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
27. 27.💡 A red LED uses 2 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
28. 28.📏 Which unit measures current? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
29. 29.🧩 Which component senses how hot it is? (a) transistor (b) buzzer (c) thermistor (d) motor
30. 30.📏 How many amperes (A) is 1560 mA? =
31. 31.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧮 Resistors of 100 Ω, 20 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
33. 33.💡 What does LED stand for? (a) light-emitting diode (b) low energy device (c) large electric dial (d) light energy dial
34. 34.🌈 A resistor has the colour bands green, brown, yellow. What is its value in kilo-ohms (kΩ)? =
35. 35.True or false: resistance is measured in ohms (Ω). (a) False (b) True
36. 36.True or false: to leave fridge door open saves electricity. (a) False (b) True
37. 37.Which of these is measured in ohms (Ω)? (a) resistance (b) current (c) power (d) voltage
38. 38.True or false: the ammeter is joined in series. (a) True (b) False
39. 39.🔺 A 6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
40. 40.True or false: the ammeter measures voltage. (a) False (b) True

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