Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 51 · 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 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🌈 In the resistor colour code, which number does violet stand for?
3. 3.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
4. 4.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
5. 5.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the tap handle (c) the pipe colour (d) the water tank lid
6. 6.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
7. 7.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
8. 8.🔺 A current of 0.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
9. 9.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V × I (d) P = V + I
10. 10.🔺 A 24 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
11. 11.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
12. 12.🌈 A resistor has the colour bands green, green, orange. What is its value (in ohms)?
13. 13.⚡ A 0.75 W device works on 1.5 V. What current does it take (in amperes)? =
14. 14.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
15. 15.🌈 A resistor has the colour bands brown, green, red. What is its value in kilo-ohms (kΩ)? =
16. 16.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
17. 17.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
18. 18.True or false: the ammeter is joined in series. (a) False (b) True
19. 19.🧮 Resistors of 10 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
20. 20.True or false: to use old filament bulbs saves electricity. (a) False (b) True
21. 21.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
22. 22.🧮 A 5 V battery is joined to 10 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
23. 23.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🔺 A current of 1.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
25. 25.📏 Which unit measures how much a part resists? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
26. 26.True or false: to set the AC to 24 °C wastes electricity. (a) False (b) True
27. 27.🌈 A resistor has the colour bands yellow, red, brown. What is its value (in ohms)?
28. 28.True or false: the ammeter measures current. (a) False (b) True
29. 29.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
31. 31.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) low energy device (d) light energy dial
32. 32.🌈 A resistor has the colour bands grey, white, black. What is its value (in ohms)?
33. 33.🧩 Which component limits the current? (a) LED (b) diode (c) potentiometer (d) resistor
34. 34.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the colour of light (d) the length of a wire
35. 35.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
36. 36.🧾 A 100 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
37. 37.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
38. 38.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
39. 39.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
40. 40.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?

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