Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 429 · 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 12 V and takes 0.2 A. What is its power (in watts)? =
2. 2.🌈 A resistor has the colour bands brown, blue, red. What is its value in kilo-ohms (kΩ)? =
3. 3.True or false: how much a part resists is measured in ohms (Ω). (a) True (b) False
4. 4.🌈 A resistor has the colour bands violet, red, red. What is its value in kilo-ohms (kΩ)? =
5. 5.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
6. 6.True or false: the ammeter is joined in series. (a) False (b) True
7. 7.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
8. 8.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
9. 9.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
10. 10.💡 An LED is joined to a 6 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
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 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
13. 13.True or false: the voltmeter is joined across a part. (a) False (b) True
14. 14.🔺 A current of 10 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🌈 In the resistor colour code, which number does white stand for?
16. 16.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I
17. 17.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
18. 18.🧮 Resistors of 33 Ω, 220 Ω, 470 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
19. 19.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
20. 20.🌈 In the resistor colour code, which number does black stand for?
21. 21.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
22. 22.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🌈 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
24. 24.🔍 Which is the odd one out? (a) unplug idle chargers (b) set the AC to 24 °C (c) use daylight to read (d) leave the TV on standby
25. 25.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) zero (d) stay the same
26. 26.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
27. 27.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = V + I (d) R = I ÷ V
28. 28.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
29. 29.🔺 A current of 25 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
31. 31.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
32. 32.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
33. 33.What does a diode do? (a) smooths a wobbly supply (b) lets current go one way (c) makes things spin (d) is a resistance knob
34. 34.⚡ A 5 W device works on 5 V. What current does it take (in amperes)? =
35. 35.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V + R (c) I = V × R (d) I = R ÷ V
36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 57000 Ω resistor? (a) violet-green-orange (b) green-violet-orange (c) green-violet-yellow (d) green-violet-red
37. 37.🧮 A 1.8 V battery is joined to 10 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
38. 38.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
40. 40.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?

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