Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 184 · 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 wastes electricity? (a) set the AC to 24 °C (b) run fans in empty rooms (c) unplug idle chargers (d) switch off empty rooms
2. 2.🌈 A resistor has the colour bands white, brown, brown. What is its value (in ohms)?
3. 3.🔍 Which is the odd one out? (a) use LED lamps (b) leave fridge door open (c) run fans in empty rooms (d) iron one shirt at a time
4. 4.🌈 In the resistor colour code, which number does blue stand for?
5. 5.🔺 A 2.5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
6. 6.True or false: how much a part resists is measured in ohms (Ω). (a) True (b) False
7. 7.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
8. 8.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
9. 9.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
10. 10.🔺 A 3 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
11. 11.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
12. 12.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
13. 13.Which of these wastes electricity? (a) close the fridge quickly (b) iron one shirt at a time (c) unplug idle chargers (d) use LED lamps
14. 14.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
15. 15.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it does not light (d) it makes a sound
16. 16.🔍 Which is the odd one out? (a) use daylight to read (b) switch off empty rooms (c) leave fridge door open (d) set the AC to 24 °C
17. 17.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.🧮 A 33 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)?
19. 19.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the one nearest an end (d) the gold band
20. 20.What does an LED do? (a) smooths a wobbly supply (b) glows using little power (c) senses how bright it is (d) makes a beeping sound
21. 21.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) measure heat (d) spin a wheel
22. 22.🧮 A 33 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)?
23. 23.🌈 A resistor has the colour bands yellow, violet, orange. What is its value in kilo-ohms (kΩ)? =
24. 24.🔺 A current of 1.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
25. 25.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
26. 26.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
27. 27.🔺 A 24 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
28. 28.True or false: a potentiometer limits the current. (a) False (b) True
29. 29.📏 How many amperes (A) is 40 mA? =
30. 30.🌈 A resistor has the colour bands brown, red, red. What is its value (in ohms)?
31. 31.🔺 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
32. 32.🔺 A 4 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
33. 33.📏 How many milliamperes (mA) is 0.85 A?
34. 34.🧮 A 220 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
35. 35.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
36. 36.📏 How many milliamperes (mA) is 2.47 A?
37. 37.🧮 A 68 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
38. 38.🔺 A 20 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
39. 39.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
40. 40.🌈 A resistor has the colour bands orange, violet, orange. What is its value in kilo-ohms (kΩ)? =

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