Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 358 · 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 R? (a) R = I ÷ V (b) R = V × I (c) R = V + I (d) R = V ÷ I
2. 2.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
3. 3.Which of these saves electricity? (a) use LED lamps (b) leave fridge door open (c) run fans in empty rooms (d) iron one shirt at a time
4. 4.True or false: how much a part resists is measured in amperes (A). (a) False (b) True
5. 5.True or false: the ammeter is joined across a part. (a) False (b) True
6. 6.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🌈 A resistor has the colour bands brown, brown, black. What is its value (in ohms)?
8. 8.⚡ A 2.4 W device works on 24 V. What current does it take (in amperes)? =
9. 9.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
10. 10.📏 Which unit measures the push of a cell? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
11. 11.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
13. 13.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
14. 14.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the gold band (d) the one nearest an end
15. 15.True or false: the ammeter is joined in series. (a) False (b) True
16. 16.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) large electric dial (d) light-emitting diode
17. 17.True or false: the voltmeter measures voltage. (a) False (b) True
18. 18.🔺 A 6 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
19. 19.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
20. 20.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
21. 21.🌈 In the resistor colour code, which number does blue stand for?
22. 22.True or false: a resistor boosts a small signal. (a) True (b) False
23. 23.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) becomes zero (d) gets bigger
24. 24.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) zero (d) smaller
25. 25.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) energy used each second (d) the length of a wire
26. 26.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
27. 27.🔺 A current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
28. 28.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
29. 29.🔺 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
30. 30.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🌈 A resistor has the colour bands green, brown, orange. What is its value (in ohms)?
32. 32.🧾 A 100 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
33. 33.True or false: to switch off empty rooms wastes electricity. (a) False (b) True
34. 34.True or false: the ammeter measures voltage. (a) True (b) False
35. 35.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity
36. 36.True or false: the voltmeter is joined in series. (a) True (b) False
37. 37.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
38. 38.Which of these wastes electricity? (a) switch off empty rooms (b) leave the TV on standby (c) close the fridge quickly (d) use LED lamps
39. 39.🔺 A 12.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
40. 40.🔺 A current of 0.5 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?

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