Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 431 · 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 gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
2. 2.🔺 A current of 0.2 A flows when 1.6 V is joined across a resistor. What is its resistance (in ohms)?
3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) stays the same (d) gets bigger
4. 4.True or false: energy used each second is measured in ohms (Ω). (a) True (b) False
5. 5.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I
6. 6.What does a capacitor do? (a) stores a little charge (b) boosts a small signal (c) makes a beeping sound (d) limits the current
7. 7.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
8. 8.🔺 A current of 3 A flows when 60 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
10. 10.True or false: a buzzer makes a beeping sound. (a) False (b) True
11. 11.⚡ A device works on 5 V and takes 0.5 A. What is its power (in watts)? =
12. 12.🌈 A resistor has the colour bands brown, green, orange. What is its value in kilo-ohms (kΩ)? =
13. 13.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
14. 14.🧩 Which component glows using little power? (a) LED (b) potentiometer (c) resistor (d) LDR
15. 15.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a buzzer (d) a diode
16. 16.Which of these is measured in volts (V)? (a) how much a part resists (b) power (c) voltage (d) current
17. 17.🔺 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
18. 18.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
19. 19.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
20. 20.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
21. 21.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) run fans in empty rooms (c) switch off empty rooms (d) close the fridge quickly
22. 22.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 100 (c) 1000 (d) 1024
23. 23.🔺 A 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
24. 24.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.Which of these saves electricity? (a) unplug idle chargers (b) leave fridge door open (c) run fans in empty rooms (d) use old filament bulbs
26. 26.⚡ A device works on 24 V and takes 0.25 A. What is its power (in watts)? =
27. 27.🔺 A current of 1.5 A flows when 4.5 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it makes a sound (d) it does not light
29. 29.🧮 Resistors of 100 Ω, 50 Ω, 100 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
30. 30.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🧮 A 470 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)?
32. 32.🧮 An 8 V battery is joined to 6 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
33. 33.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
34. 34.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
35. 35.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an oil lamp (d) an LED lamp
36. 36.🌈 A resistor has the colour bands orange, black, orange. What is its value in kilo-ohms (kΩ)? =
37. 37.🔺 A current of 0.5 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
39. 39.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🧾 A 1500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =

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