Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 137 · 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.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
2. 2.🌈 In the resistor colour code, which number does yellow stand for?
3. 3.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the widest gap (d) the gold band
4. 4.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
5. 5.Which of these is measured in amperes (A)? (a) voltage (b) the flow of charge (c) how much a part resists (d) power
6. 6.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
7. 7.Which of these saves electricity? (a) leave the TV on standby (b) use daylight to read (c) iron one shirt at a time (d) run fans in empty rooms
8. 8.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
9. 9.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
11. 11.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🌈 A resistor has the colour bands brown, black, red. What is its value in kilo-ohms (kΩ)? =
13. 13.🌈 A resistor has the colour bands grey, grey, orange. What is its value in kilo-ohms (kΩ)? =
14. 14.🔺 A 1.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
15. 15.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
16. 16.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
17. 17.🔺 A 12.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
18. 18.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
19. 19.🧮 Resistors of 22 Ω, 68 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
20. 20.⚡ A 4.5 W device works on 3 V. What current does it take (in amperes)? =
21. 21.True or false: the ammeter is joined across a part. (a) True (b) False
22. 22.📏 Which unit measures the flow of charge? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
23. 23.True or false: to switch off empty rooms saves electricity. (a) True (b) False
24. 24.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
25. 25.Which of these wastes electricity? (a) close the fridge quickly (b) use daylight to read (c) leave the TV on standby (d) use LED lamps
26. 26.📏 How many kilowatts (kW) is 750 W? =
27. 27.🔍 Which is the odd one out? (a) switch off empty rooms (b) use LED lamps (c) leave the TV on standby (d) use daylight to read
28. 28.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
29. 29.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) large electric dial (d) low energy device
30. 30.🔺 A current of 0.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.True or false: current is measured in amperes (A). (a) True (b) False
32. 32.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) gets smaller (d) becomes zero
33. 33.🔺 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
34. 34.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
35. 35.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 10 (c) 100 (d) 1024
36. 36.🧮 Resistors of 330 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🌈 In the resistor colour code, which number does brown stand for?
39. 39.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
40. 40.🔺 A current of 2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =

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