Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 288 · 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 LED stand for? (a) light energy dial (b) light-emitting diode (c) large electric dial (d) low energy device
2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 400 Ω resistor? (a) yellow-black-red (b) green-yellow-brown (c) yellow-black-black (d) yellow-black-brown
3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 490 Ω resistor? (a) yellow-white-red (b) yellow-white-black (c) white-yellow-brown (d) yellow-white-brown
4. 4.Which of these wastes electricity? (a) set the AC to 24 °C (b) unplug idle chargers (c) run fans in empty rooms (d) switch off empty rooms
5. 5.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
6. 6.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
7. 7.📏 How many ohms (Ω) is 9.9 kΩ?
8. 8.🔺 A current of 2 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
10. 10.🔺 A current of 0.5 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
11. 11.🔺 A current of 2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V ÷ I (c) R = I ÷ V (d) R = V × I
13. 13.🔺 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
14. 14.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an LED lamp (d) an oil lamp
16. 16.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
17. 17.What does a motor do? (a) limits the current (b) makes things spin (c) senses how bright it is (d) senses how hot it is
18. 18.🔺 A 16 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
19. 19.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a fuse (d) a motor
20. 20.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
21. 21.💡 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)?
22. 22.What does a buzzer do? (a) makes a beeping sound (b) blows if current is high (c) stores a little charge (d) lets current go one way
23. 23.True or false: to use LED lamps wastes electricity. (a) True (b) False
24. 24.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1000 (d) 1024
25. 25.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
26. 26.🌈 A resistor has the colour bands white, red, orange. What is its value in kilo-ohms (kΩ)? =
27. 27.📏 Which unit measures voltage? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
28. 28.🧩 Which component smooths a wobbly supply? (a) buzzer (b) fuse (c) capacitor (d) potentiometer
29. 29.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
30. 30.🧾 A family uses 30 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
31. 31.📏 Which unit measures energy used each second? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
32. 32.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
33. 33.🧾 A family uses 120 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
34. 34.🌈 In the resistor colour code, which number does white stand for?
35. 35.📏 How many ohms (Ω) is 4.2 kΩ?
36. 36.📏 How many amperes (A) is 30 mA? =
37. 37.⚡ A 27 W device works on 9 V. What current does it take (in amperes)? =
38. 38.📏 How many kilo-ohms (kΩ) is 8900 Ω? =
39. 39.🧮 A 1 V battery is joined to 2 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
40. 40.🌈 A resistor has the colour bands brown, red, yellow. What is its value in kilo-ohms (kΩ)? =

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