Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 614 · 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 does LED stand for? (a) light energy dial (b) low energy device (c) large electric dial (d) light-emitting diode
2. 2.⚡ 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
3. 3.🧮 A 10 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
4. 4.Which of these is measured in volts (V)? (a) power (b) the push of a cell (c) the flow of charge (d) energy used each second
5. 5.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
6. 6.True or false: resistance is measured in ohms (Ω). (a) False (b) True
7. 7.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
8. 8.🔍 Which is the odd one out? (a) iron one shirt at a time (b) use LED lamps (c) run fans in empty rooms (d) use old filament bulbs
9. 9.🧮 Resistors of 470 Ω, 68 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
10. 10.📏 Which unit measures how much a part resists? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
11. 11.True or false: energy used each second is measured in amperes (A). (a) False (b) True
12. 12.🔺 A 0.8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 2400 Ω resistor? (a) red-yellow-brown (b) red-yellow-orange (c) red-yellow-red (d) yellow-red-red
14. 14.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
15. 15.🌈 A resistor has the colour bands red, green, orange. What is its value in kilo-ohms (kΩ)? =
16. 16.⚡ A 1.5 W device works on 1.5 V. What current does it take (in amperes)? =
17. 17.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
18. 18.True or false: to leave the TV on standby saves electricity. (a) True (b) False
19. 19.🌈 A resistor has the colour bands yellow, violet, red. What is its value in kilo-ohms (kΩ)? =
20. 20.🔺 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
21. 21.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to store charge (d) to make it brighter
22. 22.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🧾 A 200 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
25. 25.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
26. 26.True or false: an LED senses how hot it is. (a) False (b) True
27. 27.🧮 Resistors of 68 Ω, 100 Ω, 150 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
28. 28.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
29. 29.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
30. 30.True or false: an LED senses how bright it is. (a) True (b) False
31. 31.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V × I (c) R = V ÷ I (d) R = V + I
34. 34.🌈 A resistor has the colour bands blue, orange, black. What is its value (in ohms)?
35. 35.🧾 A 1000 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
36. 36.🧾 A 100 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
37. 37.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
38. 38.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) an LED (d) a motor
39. 39.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.True or false: how much a part resists is measured in volts (V). (a) False (b) True

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