Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 587 · 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.⚡ 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
2. 2.🔍 Which is the odd one out? (a) unplug idle chargers (b) leave fridge door open (c) iron one shirt at a time (d) run fans in empty rooms
3. 3.🧾 A 100 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
4. 4.🧮 A 100 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)?
5. 5.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
6. 6.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a diode (d) a resistor
7. 7.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
9. 9.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) spin a wheel (d) store charge briefly
10. 10.🌈 A resistor has the colour bands violet, brown, yellow. What is its value in kilo-ohms (kΩ)? =
11. 11.⚡ A device works on 3 V and takes 2 A. What is its power (in watts)? =
12. 12.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
13. 13.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) power (c) resistance (d) the flow of charge
14. 14.🔺 A current of 3 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) the widest gap (d) any band
17. 17.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
18. 18.🧩 Which component lets current go one way? (a) LDR (b) resistor (c) thermistor (d) diode
19. 19.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
20. 20.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
21. 21.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
22. 22.🧮 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)?
23. 23.🔺 A 0.8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
24. 24.True or false: how much a part resists is measured in ohms (Ω). (a) True (b) False
25. 25.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
26. 26.True or false: the voltmeter measures current. (a) True (b) False
27. 27.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
28. 28.What does a thermistor do? (a) has coloured bands (b) glows using little power (c) turns a fan or wheels (d) senses how hot it is
29. 29.🔺 An 8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
30. 30.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
31. 31.📏 How many kilo-ohms (kΩ) is 6200 Ω? =
32. 32.True or false: to switch off empty rooms saves electricity. (a) False (b) True
33. 33.True or false: to use old filament bulbs wastes electricity. (a) True (b) False
34. 34.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) light energy dial (d) low energy device
35. 35.🔺 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
36. 36.True or false: a potentiometer senses how bright it is. (a) True (b) False
37. 37.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) power (c) energy used each second (d) how much a part resists
38. 38.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🧮 A 4 V battery is joined to 8 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
40. 40.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?

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