Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 580 · 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 component makes a beeping sound? (a) capacitor (b) LED (c) motor (d) buzzer
2. 2.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
3. 3.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) the one nearest an end (d) any band
4. 4.Which of these is measured in watts (W)? (a) voltage (b) the flow of charge (c) the push of a cell (d) energy used each second
5. 5.⚡ A device works on 24 V and takes 2 A. What is its power (in watts)? =
6. 6.📏 Which unit measures how much a part resists? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
7. 7.True or false: to use old filament bulbs wastes electricity. (a) True (b) False
8. 8.🔺 A current of 2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
9. 9.True or false: to use LED lamps wastes electricity. (a) False (b) True
10. 10.📏 How many ohms (Ω) is 2.5 kΩ?
11. 11.🧩 Which component glows using little power? (a) transistor (b) LED (c) capacitor (d) fuse
12. 12.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
13. 13.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a motor (d) a fuse
14. 14.Which of these saves electricity? (a) run fans in empty rooms (b) use old filament bulbs (c) leave the TV on standby (d) unplug idle chargers
15. 15.🔺 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
16. 16.🔺 A 20 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
17. 17.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
18. 18.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
20. 20.True or false: a capacitor lets current go one way. (a) True (b) False
21. 21.True or false: a potentiometer is a resistance knob. (a) False (b) True
22. 22.💡 An LED is joined to a 12 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) does not light (c) may burn out
23. 23.🧮 A 1.3 V battery is joined to 8 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
24. 24.Which of these saves electricity? (a) run fans in empty rooms (b) use old filament bulbs (c) use daylight to read (d) leave fridge door open
25. 25.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = V + I (d) P = I ÷ V
26. 26.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
27. 27.🧩 Which component senses how bright it is? (a) transistor (b) thermistor (c) LDR (d) motor
28. 28.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) an LED lamp (d) a filament bulb
29. 29.🔺 A current of 1.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🧮 Resistors of 100 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
31. 31.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
32. 32.🧮 A 220 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)?
33. 33.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
34. 34.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
35. 35.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
36. 36.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
37. 37.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
39. 39.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1000 (c) 10 (d) 1024
40. 40.Which of these wastes electricity? (a) use LED lamps (b) set the AC to 24 °C (c) close the fridge quickly (d) leave fridge door open

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