Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 125 · 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.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it changes colour (d) it does not light
2. 2.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
3. 3.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
4. 4.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 71 Ω resistor? (a) violet-brown-black (b) violet-brown-brown (c) brown-violet-black (d) grey-brown-black
5. 5.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
6. 6.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
7. 7.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
8. 8.⚡ A 27 W device works on 9 V. What current does it take (in amperes)? =
9. 9.📏 Which unit measures power? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
10. 10.What does a resistor do? (a) stores a little charge (b) makes things spin (c) has coloured bands (d) glows using little power
11. 11.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5500 Ω resistor? (a) green-blue-red (b) green-green-brown (c) green-green-red (d) green-green-orange
13. 13.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) unplug idle chargers (c) switch off empty rooms (d) leave the TV on standby
14. 14.📏 How many amperes (A) is 1180 mA? =
15. 15.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = V ÷ R (d) I = R ÷ V
16. 16.📏 How many kilo-ohms (kΩ) is 6800 Ω? =
17. 17.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
18. 18.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
19. 19.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
20. 20.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.🔺 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
22. 22.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
23. 23.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) a resistor (d) an LED
24. 24.📏 How many kilo-ohms (kΩ) is 3500 Ω? =
25. 25.🧮 A 22 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)?
26. 26.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to change its colour (d) to make it brighter
27. 27.📏 How many watts (W) is 1.6 kW?
28. 28.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
29. 29.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
30. 30.Which of these saves electricity? (a) use old filament bulbs (b) leave fridge door open (c) iron one shirt at a time (d) use LED lamps
31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 10000 Ω resistor? (a) red-brown-orange (b) brown-black-red (c) brown-black-orange (d) brown-black-yellow
32. 32.🔺 A 10 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
33. 33.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
34. 34.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
36. 36.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
37. 37.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = I ÷ V (d) R = V + I
38. 38.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 watt (d) 1 ampere
40. 40.🔍 Which is the odd one out? (a) iron one shirt at a time (b) use old filament bulbs (c) run fans in empty rooms (d) close the fridge quickly

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