Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 813 · 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 current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
3. 3.True or false: to run fans in empty rooms wastes electricity. (a) True (b) False
4. 4.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
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.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
7. 7.🧮 A 47 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)?
8. 8.🌈 In the resistor colour code, which number does blue stand for?
9. 9.🧮 Resistors of 20 Ω, 22 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
10. 10.🧮 A 20 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
11. 11.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
12. 12.🌈 In the resistor colour code, which number does red stand for?
13. 13.🌈 A resistor has the colour bands violet, red, black. What is its value (in ohms)?
14. 14.📏 How many watts (W) is 1.1 kW?
15. 15.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
16. 16.📏 Which unit measures energy used each second? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
17. 17.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
18. 18.True or false: the ammeter measures current. (a) False (b) True
19. 19.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) lights up (c) does not light
20. 20.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
21. 21.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) store charge briefly (d) measure heat
22. 22.🧩 Which component beeps for an alarm? (a) diode (b) LDR (c) capacitor (d) buzzer
23. 23.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
24. 24.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
25. 25.True or false: to unplug idle chargers saves electricity. (a) False (b) True
26. 26.🧮 A 330 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
27. 27.⚡ A device works on 3 V and takes 3 A. What is its power (in watts)? =
28. 28.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light energy dial (d) light-emitting diode
29. 29.🔺 A 12.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
30. 30.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
31. 31.What does a diode do? (a) makes a beeping sound (b) stores a little charge (c) lets current go one way (d) has coloured bands
32. 32.🔺 A 6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
33. 33.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
34. 34.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = V + I (d) P = I ÷ V
35. 35.Which of these is measured in watts (W)? (a) how much a part resists (b) power (c) resistance (d) the flow of charge
36. 36.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🧮 A 15 V battery is joined to 3 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
38. 38.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
39. 39.What does a motor do? (a) lets current go one way (b) senses how bright it is (c) has coloured bands (d) makes things spin
40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 780 Ω resistor? (a) violet-grey-red (b) grey-violet-brown (c) violet-grey-brown (d) violet-grey-black

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