Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 522 · 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) switch off empty rooms (c) use LED lamps (d) leave the TV on standby
2. 2.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) the colour of light (d) energy used each second
3. 3.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
4. 4.True or false: a capacitor stores a little charge. (a) False (b) True
5. 5.🧮 A 330 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
6. 6.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
7. 7.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
8. 8.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 watt (d) 1 kilowatt-hour (kWh)
9. 9.What does a transistor do? (a) stores a little charge (b) smooths a wobbly supply (c) senses how bright it is (d) boosts a small signal
10. 10.💡 Does it save or waste electricity to leave fridge door open? (a) wastes electricity (b) saves electricity
11. 11.🔺 A 15 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
12. 12.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
13. 13.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
14. 14.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
15. 15.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🌈 A resistor has the colour bands white, black, red. What is its value in kilo-ohms (kΩ)? =
17. 17.🧩 Which component limits the current? (a) buzzer (b) resistor (c) motor (d) LED
18. 18.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🌈 A resistor has the colour bands green, red, red. What is its value in kilo-ohms (kΩ)? =
20. 20.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4900 Ω resistor? (a) yellow-white-red (b) white-yellow-red (c) yellow-white-brown (d) yellow-white-orange
22. 22.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = R ÷ I (c) V = I × R (d) V = I ÷ R
23. 23.True or false: the ammeter measures voltage. (a) True (b) False
24. 24.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
25. 25.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
26. 26.🔺 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
27. 27.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 1000 (c) 10 (d) 60
28. 28.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🔺 A current of 0.2 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
31. 31.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
32. 32.🧮 A 16 V battery is joined to 10 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
33. 33.🧮 A 5 V battery is joined to 12 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
34. 34.Which of these is measured in amperes (A)? (a) the flow of charge (b) how much a part resists (c) resistance (d) power
35. 35.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a motor (d) a resistor
36. 36.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) zero (d) stay the same
37. 37.🧮 Resistors of 10 Ω, 470 Ω, 20 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
38. 38.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
40. 40.🧮 Resistors of 330 Ω, 33 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?

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