Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 518 · 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.True or false: the push of a cell is measured in volts (V). (a) True (b) False
2. 2.⚡ A device works on 12 V and takes 0.25 A. What is its power (in watts)? =
3. 3.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
4. 4.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) spin a wheel (d) store charge briefly
5. 5.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
6. 6.True or false: the ammeter is joined across a part. (a) False (b) True
7. 7.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I + R (d) V = I × R
8. 8.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
9. 9.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end
11. 11.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 10 (c) 1000 (d) 60
13. 13.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
14. 14.🔍 Which is the odd one out? (a) use LED lamps (b) switch off empty rooms (c) run fans in empty rooms (d) close the fridge quickly
15. 15.True or false: the voltmeter measures voltage. (a) False (b) True
16. 16.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to limit the current (d) to make it brighter
17. 17.🧩 Which component glows using little power? (a) fuse (b) capacitor (c) transistor (d) LED
18. 18.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 volt (d) 1 kilowatt-hour (kWh)
19. 19.🔺 A current of 50 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.📏 Which unit measures power? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
21. 21.🧮 A 100 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
22. 22.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
23. 23.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
24. 24.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
25. 25.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
26. 26.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water pressure (c) the water tank lid (d) the tap handle
27. 27.True or false: current is measured in ohms (Ω). (a) False (b) True
28. 28.📏 Which unit measures current? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
29. 29.🔺 A current of 1.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🧩 Which component smooths a wobbly supply? (a) transistor (b) LED (c) capacitor (d) thermistor
31. 31.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
33. 33.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.📏 How many milliamperes (mA) is 1.36 A?
35. 35.What does a capacitor do? (a) lets current go one way (b) smooths a wobbly supply (c) makes things spin (d) limits the current
36. 36.True or false: voltage is measured in volts (V). (a) True (b) False
37. 37.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the water pressure (c) a narrow pipe (d) the flow of water
38. 38.⚡ A 6 W device works on 24 V. What current does it take (in amperes)? =
39. 39.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
40. 40.True or false: the ammeter measures current. (a) True (b) False

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