Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 528 · 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 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
4. 4.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = I ÷ V (d) P = V + I
5. 5.💡 A red LED uses 2 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
6. 6.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.⚡ A 2.25 W device works on 1.5 V. What current does it take (in amperes)? =
8. 8.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) an oil lamp (d) a filament bulb
9. 9.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
10. 10.🌈 A resistor has the colour bands orange, orange, red. What is its value in kilo-ohms (kΩ)? =
11. 11.🧮 Resistors of 330 Ω, 330 Ω, 20 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
12. 12.🧾 A family uses 150 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
13. 13.📏 Which unit measures energy used each second? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
14. 14.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
15. 15.📏 How many kilowatts (kW) is 1750 W? =
16. 16.🌈 A resistor has the colour bands grey, yellow, orange. What is its value (in ohms)?
17. 17.True or false: to use old filament bulbs saves electricity. (a) True (b) False
18. 18.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
20. 20.🧮 A 22 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
21. 21.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?
22. 22.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =
23. 23.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
24. 24.🌈 In the resistor colour code, which number does black stand for?
25. 25.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🌈 In the resistor colour code, which number does red stand for?
27. 27.True or false: the ammeter is joined in series. (a) True (b) False
28. 28.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
29. 29.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
30. 30.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it makes a sound (d) it lights brighter
31. 31.⚡ 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
32. 32.🌈 A resistor has the colour bands brown, grey, red. What is its value (in ohms)?
33. 33.🧮 A 330 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
34. 34.Which of these is measured in ohms (Ω)? (a) current (b) the push of a cell (c) the flow of charge (d) how much a part resists
35. 35.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
36. 36.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to change its colour (d) to limit the current
37. 37.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a fuse (d) a resistor
39. 39.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
40. 40.💡 An LED is joined to a 6 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up

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