Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 368 · 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.📏 How many ohms (Ω) is 6.7 kΩ?
2. 2.True or false: the voltmeter measures voltage. (a) False (b) True
3. 3.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the widest gap (d) the gold band
4. 4.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
5. 5.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
6. 6.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
7. 7.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
8. 8.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = R ÷ I (d) V = I × R
9. 9.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 35 Ω resistor? (a) orange-green-black (b) orange-green-brown (c) yellow-green-black (d) green-orange-black
11. 11.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🔺 A current of 50 mA flows when 11 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.🌈 A resistor has the colour bands orange, black, yellow. What is its value in kilo-ohms (kΩ)? =
14. 14.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
15. 15.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
16. 16.💡 An LED is joined to a 6 V battery through a 330 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) may burn out (c) does not light
17. 17.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it changes colour (d) it lights brighter
18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 5 % (d) 0 %
19. 19.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a resistor (d) a diode
20. 20.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
21. 21.Which of these is measured in watts (W)? (a) how much a part resists (b) power (c) the flow of charge (d) voltage
22. 22.Which of these saves electricity? (a) use old filament bulbs (b) leave fridge door open (c) use daylight to read (d) run fans in empty rooms
23. 23.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
24. 24.🧾 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
25. 25.⚡ A 1.2 W device works on 12 V. What current does it take (in amperes)? =
26. 26.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.💡 What does LED stand for? (a) light-emitting diode (b) low energy device (c) large electric dial (d) light energy dial
28. 28.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to store charge (d) to change its colour
29. 29.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
30. 30.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
31. 31.🔍 Which is the odd one out? (a) leave fridge door open (b) switch off empty rooms (c) use old filament bulbs (d) run fans in empty rooms
32. 32.🔺 A current of 2 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) bigger (d) stay the same
34. 34.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) use daylight to read (c) run fans in empty rooms (d) unplug idle chargers
35. 35.True or false: an LED glows using little power. (a) False (b) True
36. 36.🧾 A 50 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
37. 37.🔺 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
38. 38.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
40. 40.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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