Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 91 · 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 device works on 3 V and takes 0.2 A. What is its power (in watts)? =
2. 2.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) the gold band (d) any band
3. 3.🌈 In the resistor colour code, which number does orange stand for?
4. 4.📏 How many kilowatts (kW) is 4200 W? =
5. 5.⚡ A 1 W device works on 5 V. What current does it take (in amperes)? =
6. 6.🔍 Which is the odd one out? (a) use old filament bulbs (b) iron one shirt at a time (c) leave fridge door open (d) set the AC to 24 °C
7. 7.True or false: a motor turns a fan or wheels. (a) True (b) False
8. 8.True or false: the ammeter measures current. (a) True (b) False
9. 9.🔺 A current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V + R (d) I = V × R
11. 11.🧮 A 20 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
12. 12.🧮 A 47 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
13. 13.🔍 Which is the odd one out? (a) use LED lamps (b) leave fridge door open (c) run fans in empty rooms (d) leave the TV on standby
14. 14.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) gets smaller (d) becomes zero
16. 16.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it does not light (d) it changes colour
17. 17.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
18. 18.🔺 A 9 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
19. 19.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to make it brighter (d) to limit the current
20. 20.📏 Which unit measures how much a part resists? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
21. 21.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the pipe colour (c) the tap handle (d) the water tank lid
22. 22.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 54000 Ω resistor? (a) green-yellow-orange (b) green-yellow-red (c) green-yellow-yellow (d) yellow-green-orange
25. 25.📏 How many kilowatts (kW) is 2600 W? =
26. 26.📏 How many amperes (A) is 2840 mA? =
27. 27.📏 Which unit measures voltage? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
28. 28.🔍 Which is the odd one out? (a) leave fridge door open (b) unplug idle chargers (c) use daylight to read (d) set the AC to 24 °C
29. 29.📏 How many milliamperes (mA) is 0.86 A?
30. 30.🔺 A 15 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
31. 31.🌈 A resistor has the colour bands blue, yellow, orange. What is its value (in ohms)?
32. 32.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
33. 33.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a fuse (d) a motor
34. 34.🧮 Resistors of 10 Ω, 33 Ω, 220 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
35. 35.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
36. 36.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
37. 37.💡 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)?
38. 38.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) smaller (d) bigger
39. 39.🌈 A resistor has the colour bands yellow, blue, red. What is its value (in ohms)?
40. 40.💡 A red LED uses 2 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?

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