Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 795 · 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.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a buzzer (d) a diode
3. 3.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
4. 4.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a resistor (d) a motor
5. 5.🧩 Which component senses how bright it is? (a) LDR (b) resistor (c) capacitor (d) buzzer
6. 6.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.Which of these saves electricity? (a) use old filament bulbs (b) use daylight to read (c) iron one shirt at a time (d) leave the TV on standby
8. 8.🌈 In the resistor colour code, which number does red stand for?
9. 9.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 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
11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 12000 Ω resistor? (a) brown-red-orange (b) brown-red-yellow (c) brown-red-red (d) red-brown-orange
12. 12.🧮 Resistors of 47 Ω, 330 Ω, 100 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
13. 13.Which of these saves electricity? (a) use old filament bulbs (b) unplug idle chargers (c) leave fridge door open (d) iron one shirt at a time
14. 14.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an LED lamp (d) an oil lamp
15. 15.📏 Which unit measures how much a part resists? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
16. 16.True or false: the voltmeter is joined across a part. (a) False (b) True
17. 17.🌈 In the resistor colour code, which number does blue stand for?
18. 18.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 10 (c) 100 (d) 1024
19. 19.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
20. 20.🌈 A resistor has the colour bands white, yellow, red. What is its value (in ohms)?
21. 21.📏 How many milliamperes (mA) is 1.46 A?
22. 22.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
23. 23.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
24. 24.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
25. 25.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
26. 26.Which of these is measured in amperes (A)? (a) power (b) the push of a cell (c) the flow of charge (d) energy used each second
27. 27.🧮 A 470 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
28. 28.🔍 Which is the odd one out? (a) run fans in empty rooms (b) switch off empty rooms (c) use old filament bulbs (d) leave the TV on standby
29. 29.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🌈 A resistor has the colour bands orange, yellow, red. What is its value in kilo-ohms (kΩ)? =
31. 31.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
33. 33.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
34. 34.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
35. 35.🔺 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
36. 36.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) make light (d) spin a wheel
39. 39.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🧾 A family uses 150 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?

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