Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 758 · 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.What does a capacitor do? (a) makes a beeping sound (b) lets current go one way (c) makes things spin (d) smooths a wobbly supply
2. 2.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
3. 3.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
4. 4.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
5. 5.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
7. 7.📏 Which unit measures voltage? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
8. 8.True or false: a thermistor has coloured bands. (a) True (b) False
9. 9.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light-emitting diode (d) light energy dial
10. 10.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
11. 11.⚡ A 1.5 W device works on 1.5 V. What current does it take (in amperes)? =
12. 12.⚡ A device works on 24 V and takes 2 A. What is its power (in watts)? =
13. 13.📏 Which unit measures current? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
14. 14.🔺 A 3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
15. 15.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
16. 16.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
17. 17.🌈 A resistor has the colour bands violet, red, red. What is its value in kilo-ohms (kΩ)? =
18. 18.Which of these saves electricity? (a) leave fridge door open (b) leave the TV on standby (c) use LED lamps (d) use old filament bulbs
19. 19.🧩 Which component boosts a small signal? (a) LDR (b) motor (c) buzzer (d) transistor
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 65000 Ω resistor? (a) blue-green-red (b) green-blue-orange (c) blue-green-yellow (d) blue-green-orange
21. 21.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the length of a wire (d) the size of a cell
22. 22.Which of these is measured in watts (W)? (a) the push of a cell (b) voltage (c) power (d) the flow of charge
23. 23.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
24. 24.🌈 A resistor has the colour bands green, black, brown. What is its value (in ohms)?
25. 25.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
26. 26.🧩 Which component has coloured bands? (a) diode (b) motor (c) resistor (d) fuse
27. 27.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a resistor (d) a fuse
28. 28.True or false: the flow of charge is measured in amperes (A). (a) True (b) False
29. 29.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🧮 A 2.75 V battery is joined to 3 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
32. 32.🌈 A resistor has the colour bands red, black, orange. What is its value in kilo-ohms (kΩ)? =
33. 33.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🧮 A 6.5 V battery is joined to 5 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
35. 35.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🧮 Resistors of 150 Ω, 33 Ω, 20 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
38. 38.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
39. 39.True or false: resistance is measured in ohms (Ω). (a) True (b) False
40. 40.🧩 A capacitor in a circuit can … (a) spin a wheel (b) measure heat (c) store charge briefly (d) make light

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