Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 546 · 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.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
3. 3.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it does not light (d) it makes a sound
4. 4.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
6. 6.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
7. 7.What does a diode do? (a) makes a beeping sound (b) boosts a small signal (c) lets current go one way (d) smooths a wobbly supply
8. 8.What does a capacitor do? (a) senses how hot it is (b) senses how bright it is (c) limits the current (d) stores a little charge
9. 9.Which of these is measured in watts (W)? (a) voltage (b) the push of a cell (c) power (d) the flow of charge
10. 10.💡 What does LED stand for? (a) low energy device (b) light-emitting diode (c) light energy dial (d) large electric dial
11. 11.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) less than either one (d) always zero
12. 12.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
13. 13.🔺 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
14. 14.📏 How many kilowatts (kW) is 3150 W? =
15. 15.🔍 Which is the odd one out? (a) close the fridge quickly (b) switch off empty rooms (c) use old filament bulbs (d) use LED lamps
16. 16.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
17. 17.🔺 A current of 40 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
19. 19.🌈 A resistor has the colour bands grey, blue, red. What is its value in kilo-ohms (kΩ)? =
20. 20.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
21. 21.Which of these saves electricity? (a) leave the TV on standby (b) run fans in empty rooms (c) unplug idle chargers (d) use old filament bulbs
22. 22.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?
23. 23.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
24. 24.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) energy used each second (d) the length of a wire
25. 25.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) any band (d) the widest gap
26. 26.🧮 A 1 V battery is joined to 2 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
27. 27.🧮 Resistors of 150 Ω, 220 Ω, 220 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
28. 28.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1900 Ω resistor? (a) brown-white-red (b) brown-white-brown (c) brown-white-orange (d) white-brown-red
31. 31.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
32. 32.🔺 A current of 40 mA flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.True or false: the voltmeter is joined in series. (a) False (b) True
34. 34.⚡ A device works on 6 V and takes 0.25 A. What is its power (in watts)? =
35. 35.📏 How many amperes (A) is 640 mA? =
36. 36.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
37. 37.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to limit the current (d) to change its colour
38. 38.True or false: power is measured in amperes (A). (a) True (b) False
39. 39.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) gets smaller (d) stays the same

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