Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 682 · 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.True or false: the voltmeter measures voltage. (a) True (b) False
2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 480 Ω resistor? (a) yellow-grey-red (b) yellow-grey-black (c) grey-yellow-brown (d) yellow-grey-brown
3. 3.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
4. 4.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) current (c) the push of a cell (d) how much a part resists
5. 5.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a capacitor (c) a diode (d) a resistor
6. 6.True or false: a potentiometer is a resistance knob. (a) True (b) False
7. 7.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V × I (c) R = V ÷ I (d) R = I ÷ V
8. 8.True or false: an LED has coloured bands. (a) False (b) True
9. 9.🧮 Resistors of 220 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
10. 10.🌈 In the resistor colour code, which number does red stand for?
11. 11.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🧩 Which component beeps for an alarm? (a) buzzer (b) diode (c) resistor (d) LDR
13. 13.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
14. 14.Which of these wastes electricity? (a) use LED lamps (b) set the AC to 24 °C (c) run fans in empty rooms (d) use daylight to read
15. 15.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V × I (d) P = V + I
16. 16.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🔺 A 4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
18. 18.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) use LED lamps (c) leave fridge door open (d) unplug idle chargers
19. 19.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
21. 21.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a bigger tank (c) a narrow pipe (d) the water pressure
22. 22.🧩 Which component turns a fan or wheels? (a) thermistor (b) fuse (c) motor (d) LDR
23. 23.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V × R (d) I = V ÷ R
24. 24.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
25. 25.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
26. 26.🧩 Which component limits the current? (a) LED (b) potentiometer (c) motor (d) resistor
27. 27.🌈 In the resistor colour code, which number does black stand for?
28. 28.🧮 A 50 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 17000 Ω resistor? (a) violet-brown-orange (b) brown-violet-orange (c) brown-violet-yellow (d) brown-violet-red
30. 30.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
31. 31.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light-emitting diode (d) light energy dial
32. 32.🌈 A resistor has the colour bands grey, white, orange. What is its value (in ohms)?
33. 33.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.🔺 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
35. 35.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an LED lamp (d) an oil lamp
36. 36.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
37. 37.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
38. 38.🧾 A 250 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
39. 39.🧮 A 1.3 V battery is joined to 5 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
40. 40.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it changes colour (d) it does not light

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