Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 72 · 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 V-I-R triangle, how do we find V? (a) V = I × R (b) V = I ÷ R (c) V = R ÷ I (d) V = I + R
2. 2.🔺 A 12 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
3. 3.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = R ÷ V (d) I = V ÷ R
4. 4.🧮 Resistors of 10 Ω, 10 Ω, 10 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.🔺 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
6. 6.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.True or false: to run fans in empty rooms saves electricity. (a) True (b) False
8. 8.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
11. 11.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) the widest gap (d) any band
12. 12.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) switch off empty rooms (c) use old filament bulbs (d) unplug idle chargers
13. 13.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
14. 14.True or false: an LED has coloured bands. (a) False (b) True
15. 15.True or false: the ammeter measures current. (a) True (b) False
16. 16.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 530 Ω resistor? (a) orange-green-brown (b) green-orange-black (c) green-orange-brown (d) green-orange-red
18. 18.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🌈 A resistor has the colour bands red, black, red. What is its value in kilo-ohms (kΩ)? =
20. 20.🔍 Which is the odd one out? (a) run fans in empty rooms (b) leave fridge door open (c) iron one shirt at a time (d) close the fridge quickly
21. 21.What does a transistor do? (a) boosts a small signal (b) limits the current (c) beeps for an alarm (d) has coloured bands
22. 22.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 100 (d) 1000
23. 23.🧮 Resistors of 220 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
24. 24.🧮 A 330 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)?
25. 25.🔺 A 1.5 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
26. 26.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
27. 27.True or false: a thermistor senses how bright it is. (a) False (b) True
28. 28.True or false: the ammeter is joined across a part. (a) True (b) False
29. 29.🌈 A resistor has the colour bands green, yellow, yellow. What is its value in kilo-ohms (kΩ)? =
30. 30.🧩 Which part changes electrical energy into movement? (a) a motor (b) a resistor (c) a fuse (d) an LED
31. 31.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🔺 A current of 2 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.📏 Which unit measures current? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
34. 34.True or false: voltage is measured in volts (V). (a) True (b) False
35. 35.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
36. 36.True or false: the flow of charge is measured in amperes (A). (a) True (b) False
37. 37.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🔺 A current of 0.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🌈 A resistor has the colour bands orange, brown, black. What is its value (in ohms)?
40. 40.Which of these wastes electricity? (a) unplug idle chargers (b) leave fridge door open (c) use LED lamps (d) set the AC to 24 °C

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