Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 766 · 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.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
2. 2.True or false: the voltmeter measures voltage. (a) True (b) False
3. 3.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
4. 4.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light-emitting diode (d) light energy dial
5. 5.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
6. 6.🧮 Resistors of 10 Ω, 22 Ω, 22 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
7. 7.🌈 A resistor has the colour bands brown, white, yellow. What is its value in kilo-ohms (kΩ)? =
8. 8.True or false: voltage is measured in watts (W). (a) True (b) False
9. 9.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
11. 11.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
12. 12.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) a filament bulb (d) an LED lamp
14. 14.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
15. 15.Which of these is measured in watts (W)? (a) current (b) voltage (c) how much a part resists (d) power
16. 16.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
17. 17.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) store charge briefly (d) measure heat
18. 18.🌈 A resistor has the colour bands blue, red, red. What is its value in kilo-ohms (kΩ)? =
19. 19.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a buzzer (d) a diode
20. 20.💡 An LED is joined to a 3 V battery through a 470 Ω 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
21. 21.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = I × R (d) V = R ÷ I
23. 23.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) always zero (d) less than either one
24. 24.🔍 Which is the odd one out? (a) leave the TV on standby (b) switch off empty rooms (c) leave fridge door open (d) iron one shirt at a time
25. 25.🧮 Resistors of 50 Ω, 68 Ω, 50 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8300 Ω resistor? (a) grey-orange-brown (b) orange-grey-red (c) grey-orange-red (d) grey-orange-orange
27. 27.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
28. 28.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 10 (c) 1024 (d) 100
29. 29.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
30. 30.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
31. 31.🔺 A 7.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
32. 32.🌈 A resistor has the colour bands white, red, black. What is its value (in ohms)?
33. 33.Which of these wastes electricity? (a) use daylight to read (b) switch off empty rooms (c) use LED lamps (d) leave the TV on standby
34. 34.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
35. 35.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
36. 36.🧮 Resistors of 68 Ω, 47 Ω, 10 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.What does a buzzer do? (a) blows if current is high (b) turns a fan or wheels (c) smooths a wobbly supply (d) beeps for an alarm
38. 38.Which of these wastes electricity? (a) use LED lamps (b) unplug idle chargers (c) set the AC to 24 °C (d) leave fridge door open
39. 39.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
40. 40.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?

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