Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 380 · 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: to unplug idle chargers saves electricity. (a) True (b) False
2. 2.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
3. 3.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it makes a sound (d) it does not light
4. 4.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8200 Ω resistor? (a) red-grey-red (b) grey-red-orange (c) grey-red-brown (d) grey-red-red
5. 5.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
6. 6.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
7. 7.🔺 A current of 1.5 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.What does a thermistor do? (a) beeps for an alarm (b) smooths a wobbly supply (c) stores a little charge (d) senses how hot it is
9. 9.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
10. 10.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one
11. 11.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
12. 12.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
13. 13.🌈 In the resistor colour code, which number does yellow stand for?
14. 14.🌈 A resistor has the colour bands blue, violet, black. What is its value (in ohms)?
15. 15.Which of these is measured in ohms (Ω)? (a) power (b) the flow of charge (c) energy used each second (d) resistance
16. 16.🌈 In the resistor colour code, which number does black stand for?
17. 17.🧩 Which component limits the current? (a) fuse (b) thermistor (c) resistor (d) capacitor
18. 18.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V ÷ R (c) I = R ÷ V (d) I = V × R
19. 19.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
20. 20.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🧮 Resistors of 33 Ω, 330 Ω, 68 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
22. 22.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
24. 24.🔺 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
25. 25.Which of these saves electricity? (a) use daylight to read (b) run fans in empty rooms (c) leave fridge door open (d) use old filament bulbs
26. 26.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🧾 A family uses 120 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 810 Ω resistor? (a) brown-grey-brown (b) grey-brown-black (c) grey-brown-red (d) grey-brown-brown
29. 29.📏 How many amperes (A) is 1270 mA? =
30. 30.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 10 (c) 100 (d) 60
31. 31.🌈 A resistor has the colour bands green, blue, orange. What is its value (in ohms)?
32. 32.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
33. 33.🧮 A 22 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
34. 34.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
35. 35.🌈 A resistor has the colour bands white, brown, brown. What is its value (in ohms)?
36. 36.⚡ An 18 W device works on 6 V. What current does it take (in amperes)? =
37. 37.🧾 A family uses 110 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
38. 38.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🔺 A current of 50 mA flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) an oil lamp (d) a candle

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