Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 804 · 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.🧮 Resistors of 10 Ω, 20 Ω, 33 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
2. 2.What does a potentiometer do? (a) stores a little charge (b) lets current go one way (c) is a resistance knob (d) senses how bright it is
3. 3.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
5. 5.📏 How many milliamperes (mA) is 0.75 A?
6. 6.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
7. 7.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
8. 8.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
9. 9.What does a capacitor do? (a) turns a fan or wheels (b) stores a little charge (c) senses how bright it is (d) has coloured bands
10. 10.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
11. 11.True or false: to leave the TV on standby wastes electricity. (a) False (b) True
12. 12.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
13. 13.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
14. 14.True or false: the push of a cell is measured in amperes (A). (a) False (b) True
15. 15.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
16. 16.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = R ÷ V (c) I = V + R (d) I = V ÷ R
17. 17.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
18. 18.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
19. 19.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
20. 20.⚡ A 2.5 W device works on 5 V. What current does it take (in amperes)? =
21. 21.📏 How many milliamperes (mA) is 2.97 A?
22. 22.🧮 A 330 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)?
23. 23.🧩 Which component boosts a small signal? (a) resistor (b) potentiometer (c) capacitor (d) transistor
24. 24.Which of these is measured in volts (V)? (a) the flow of charge (b) current (c) how much a part resists (d) voltage
25. 25.Which of these wastes electricity? (a) set the AC to 24 °C (b) use LED lamps (c) use daylight to read (d) use old filament bulbs
26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9000 Ω resistor? (a) white-black-brown (b) white-black-red (c) brown-white-red (d) white-black-orange
27. 27.⚡ A 9 W device works on 6 V. What current does it take (in amperes)? =
28. 28.True or false: a resistor has coloured bands. (a) True (b) False
29. 29.🧩 Which component limits the current? (a) buzzer (b) fuse (c) LED (d) resistor
30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 10 Ω resistor? (a) brown-black-brown (b) red-black-black (c) brown-black-black (d) red-brown-black
31. 31.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) smaller (d) bigger
32. 32.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I ÷ R (d) V = I + R
34. 34.🧮 Resistors of 470 Ω, 50 Ω, 220 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
35. 35.🔺 A 5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
36. 36.What does an LDR do? (a) stores a little charge (b) turns a fan or wheels (c) senses how hot it is (d) senses how bright it is
37. 37.🌈 A resistor has the colour bands blue, brown, yellow. What is its value in kilo-ohms (kΩ)? =
38. 38.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
39. 39.🧮 A 220 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
40. 40.🌈 In the resistor colour code, which number does blue stand for?

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