Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 982 · 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 of these is measured in amperes (A)? (a) resistance (b) power (c) the flow of charge (d) the push of a cell
2. 2.True or false: the ammeter is joined in series. (a) True (b) False
3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) gets bigger (d) becomes zero
4. 4.🌈 A resistor has the colour bands orange, orange, yellow. What is its value in kilo-ohms (kΩ)? =
5. 5.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
6. 6.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
7. 7.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
8. 8.True or false: to use LED lamps wastes electricity. (a) True (b) False
9. 9.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the widest gap (d) the one nearest an end
11. 11.True or false: a buzzer makes a beeping sound. (a) True (b) False
12. 12.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
13. 13.🧩 Which component glows using little power? (a) fuse (b) LED (c) capacitor (d) buzzer
14. 14.📏 Which unit measures how much a part resists? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
15. 15.🔍 Which is the odd one out? (a) unplug idle chargers (b) use daylight to read (c) leave fridge door open (d) set the AC to 24 °C
16. 16.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
17. 17.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
18. 18.🧮 A 0.9 V battery is joined to 3 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
19. 19.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) large electric dial (d) low energy device
20. 20.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
21. 21.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) measure heat (d) make light
22. 22.🌈 In the resistor colour code, which number does grey stand for?
23. 23.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
24. 24.📏 How many amperes (A) is 2730 mA? =
25. 25.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
26. 26.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to change its colour (d) to limit the current
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 250 Ω resistor? (a) red-green-brown (b) red-green-red (c) green-red-brown (d) red-green-black
28. 28.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
29. 29.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I + R (d) V = I × R
30. 30.True or false: to run fans in empty rooms saves electricity. (a) True (b) False
31. 31.🌈 A resistor has the colour bands green, blue, brown. What is its value (in ohms)?
32. 32.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
33. 33.🧮 Resistors of 470 Ω, 150 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
34. 34.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
35. 35.🌈 A resistor has the colour bands brown, blue, yellow. What is its value in kilo-ohms (kΩ)? =
36. 36.What does a diode do? (a) lets current go one way (b) is a resistance knob (c) turns a fan or wheels (d) beeps for an alarm
37. 37.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
38. 38.🔍 Which is the odd one out? (a) switch off empty rooms (b) use LED lamps (c) run fans in empty rooms (d) use daylight to read
39. 39.🔍 Which is the odd one out? (a) iron one shirt at a time (b) set the AC to 24 °C (c) run fans in empty rooms (d) leave the TV on standby
40. 40.🔺 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

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