Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 62 · 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.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = I ÷ V (c) R = V × I (d) R = V + I
2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 57 Ω resistor? (a) green-violet-brown (b) green-violet-black (c) blue-violet-black (d) violet-green-black
3. 3.True or false: the push of a cell is measured in ohms (Ω). (a) True (b) False
4. 4.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the pipe colour (c) a narrow pipe (d) the flow of water
5. 5.🔺 A current of 1 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.🔺 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
7. 7.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller
8. 8.🔺 A 20 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
9. 9.🧮 Resistors of 33 Ω, 33 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
10. 10.🧮 A 6.5 V battery is joined to 10 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
11. 11.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) spin a wheel (d) make light
12. 12.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the gold band (d) the widest gap
13. 13.Which of these wastes electricity? (a) set the AC to 24 °C (b) unplug idle chargers (c) use daylight to read (d) iron one shirt at a time
14. 14.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.What does a resistor do? (a) makes things spin (b) senses how bright it is (c) smooths a wobbly supply (d) limits the current
16. 16.🌈 A resistor has the colour bands brown, orange, orange. What is its value (in ohms)?
17. 17.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
18. 18.What does a buzzer do? (a) glows using little power (b) beeps for an alarm (c) has coloured bands (d) senses how bright it is
19. 19.🔺 A current of 25 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
21. 21.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
22. 22.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
24. 24.📏 How many kilo-ohms (kΩ) is 4500 Ω? =
25. 25.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🧾 A 50 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
27. 27.🧩 Which component makes a beeping sound? (a) motor (b) buzzer (c) fuse (d) LED
28. 28.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
29. 29.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
31. 31.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
32. 32.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
33. 33.True or false: the ammeter measures voltage. (a) False (b) True
34. 34.🧮 A 1.8 V battery is joined to 8 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
35. 35.🌈 In the resistor colour code, which number does green stand for?
36. 36.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 volt
37. 37.🧾 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?
38. 38.🌈 In the resistor colour code, which number does black stand for?
39. 39.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🧮 Resistors of 150 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?

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