Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 306 · 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 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
2. 2.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
3. 3.⚡ A 1.25 W device works on 5 V. What current does it take (in amperes)? =
4. 4.📏 Which unit measures the flow of charge? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
5. 5.Which of these saves electricity? (a) leave fridge door open (b) leave the TV on standby (c) switch off empty rooms (d) run fans in empty rooms
6. 6.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
7. 7.What does a diode do? (a) smooths a wobbly supply (b) glows using little power (c) lets current go one way (d) has coloured bands
8. 8.True or false: current is measured in volts (V). (a) True (b) False
9. 9.🌈 A resistor has the colour bands yellow, red, red. What is its value in kilo-ohms (kΩ)? =
10. 10.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
11. 11.True or false: a buzzer has coloured bands. (a) True (b) False
12. 12.🌈 In the resistor colour code, which number does grey stand for?
13. 13.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
14. 14.💡 What does LED stand for? (a) low energy device (b) light-emitting diode (c) large electric dial (d) light energy dial
15. 15.🌈 In the resistor colour code, which number does violet stand for?
16. 16.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
17. 17.🧾 A 250 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
18. 18.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.🌈 A resistor has the colour bands red, orange, red. What is its value in kilo-ohms (kΩ)? =
22. 22.True or false: a transistor boosts a small signal. (a) False (b) True
23. 23.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a filament bulb (c) an LED lamp (d) a candle
25. 25.🧮 Resistors of 22 Ω, 330 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 10 (c) 1000 (d) 100
27. 27.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
28. 28.Which of these saves electricity? (a) iron one shirt at a time (b) unplug idle chargers (c) use old filament bulbs (d) run fans in empty rooms
29. 29.📏 How many amperes (A) is 1650 mA? =
30. 30.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🌈 A resistor has the colour bands white, red, red. What is its value in kilo-ohms (kΩ)? =
32. 32.Which of these wastes electricity? (a) use LED lamps (b) close the fridge quickly (c) use daylight to read (d) use old filament bulbs
33. 33.🌈 A resistor has the colour bands yellow, red, orange. What is its value in kilo-ohms (kΩ)? =
34. 34.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) an LED (d) a resistor
35. 35.🔺 A 1 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
36. 36.What does a buzzer do? (a) stores a little charge (b) is a resistance knob (c) makes things spin (d) makes a beeping sound
37. 37.True or false: the voltmeter is joined in series. (a) True (b) False
38. 38.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
39. 39.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
40. 40.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I

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