Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 163 · 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.What does a buzzer do? (a) blows if current is high (b) senses how hot it is (c) has coloured bands (d) beeps for an alarm
2. 2.True or false: the ammeter measures voltage. (a) True (b) False
3. 3.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
4. 4.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
5. 5.🧮 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
6. 6.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
7. 7.🔺 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
8. 8.🧩 Which component lets current go one way? (a) diode (b) resistor (c) motor (d) buzzer
9. 9.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
10. 10.🔺 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
11. 11.🌈 A resistor has the colour bands green, green, orange. What is its value (in ohms)?
12. 12.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
13. 13.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
14. 14.🌈 A resistor has the colour bands orange, red, yellow. What is its value in kilo-ohms (kΩ)? =
15. 15.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
17. 17.True or false: the flow of charge is measured in volts (V). (a) False (b) True
18. 18.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) low energy device (d) light-emitting diode
19. 19.🌈 In the resistor colour code, which number does grey stand for?
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 11000 Ω resistor? (a) brown-red-orange (b) brown-brown-yellow (c) brown-brown-red (d) brown-brown-orange
21. 21.Which of these saves electricity? (a) use old filament bulbs (b) iron one shirt at a time (c) run fans in empty rooms (d) use LED lamps
22. 22.⚡ A device works on 9 V and takes 0.25 A. What is its power (in watts)? =
23. 23.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🧩 Which component turns a fan or wheels? (a) diode (b) resistor (c) transistor (d) motor
25. 25.⚡ A 0.375 W device works on 1.5 V. What current does it take (in amperes)? =
26. 26.📏 Which unit measures power? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
27. 27.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
28. 28.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
29. 29.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
30. 30.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
31. 31.📏 Which unit measures current? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
32. 32.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) run fans in empty rooms (c) use daylight to read (d) switch off empty rooms
33. 33.💡 A red LED uses 2 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
34. 34.📏 How many milliamperes (mA) is 1.35 A?
35. 35.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
36. 36.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
38. 38.Which of these wastes electricity? (a) use daylight to read (b) run fans in empty rooms (c) close the fridge quickly (d) switch off empty rooms
39. 39.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
40. 40.Which of these saves electricity? (a) iron one shirt at a time (b) use old filament bulbs (c) switch off empty rooms (d) leave the TV on standby

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