Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 107 · 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 capacitor in a circuit can … (a) store charge briefly (b) make light (c) measure heat (d) spin a wheel
2. 2.🧾 A 1000 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
3. 3.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
4. 4.🌈 In the resistor colour code, which number does brown stand for?
5. 5.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.🌈 A resistor has the colour bands violet, red, yellow. What is its value in kilo-ohms (kΩ)? =
8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4100 Ω resistor? (a) yellow-brown-orange (b) brown-yellow-red (c) yellow-brown-red (d) yellow-brown-brown
9. 9.🧾 A family uses 140 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
10. 10.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
12. 12.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
13. 13.🧮 A 1.2 V battery is joined to 6 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
14. 14.What does a motor do? (a) glows using little power (b) lets current go one way (c) makes things spin (d) limits the current
15. 15.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🔍 Which is the odd one out? (a) use LED lamps (b) switch off empty rooms (c) set the AC to 24 °C (d) use old filament bulbs
17. 17.🔺 A 12.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
18. 18.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
19. 19.📏 Which unit measures energy used each second? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
20. 20.🌈 A resistor has the colour bands violet, violet, black. What is its value (in ohms)?
21. 21.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
22. 22.🔺 A current of 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.True or false: the ammeter is joined across a part. (a) True (b) False
25. 25.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
26. 26.Which of these saves electricity? (a) leave fridge door open (b) leave the TV on standby (c) set the AC to 24 °C (d) iron one shirt at a time
27. 27.🧮 A 100 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
28. 28.🧩 Which component smooths a wobbly supply? (a) LED (b) thermistor (c) capacitor (d) resistor
29. 29.🌈 In the resistor colour code, which number does red stand for?
30. 30.Which of these is measured in ohms (Ω)? (a) resistance (b) power (c) the push of a cell (d) energy used each second
31. 31.🔺 A 1.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
32. 32.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the widest gap (d) the gold band
33. 33.🔺 A 2 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
34. 34.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
35. 35.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
36. 36.📏 How many kilowatts (kW) is 1650 W? =
37. 37.🔺 A 30 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
38. 38.🌈 A resistor has the colour bands red, violet, orange. What is its value (in ohms)?
39. 39.True or false: to close the fridge quickly wastes electricity. (a) True (b) False
40. 40.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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