Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 263 · 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 an LED do? (a) turns a fan or wheels (b) makes a beeping sound (c) smooths a wobbly supply (d) glows using little power
2. 2.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
3. 3.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
4. 4.📏 Which unit measures the push of a cell? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
5. 5.True or false: a potentiometer is a resistance knob. (a) True (b) False
6. 6.🔺 A current of 25 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.🌈 A resistor has the colour bands white, white, black. What is its value (in ohms)?
9. 9.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
11. 11.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) less than either one (d) always zero
13. 13.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
14. 14.What does a motor do? (a) stores a little charge (b) boosts a small signal (c) makes a beeping sound (d) makes things spin
15. 15.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
16. 16.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) the colour of light (d) energy used each second
17. 17.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
18. 18.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 60 (c) 100 (d) 10
19. 19.True or false: the voltmeter is joined in series. (a) False (b) True
20. 20.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to store charge (d) to change its colour
21. 21.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) the gold band (d) any band
22. 22.🔍 Which is the odd one out? (a) run fans in empty rooms (b) leave fridge door open (c) close the fridge quickly (d) use old filament bulbs
23. 23.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = V × I (d) P = I ÷ V
24. 24.🧾 A family uses 90 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
25. 25.🔍 Which is the odd one out? (a) iron one shirt at a time (b) leave the TV on standby (c) unplug idle chargers (d) leave fridge door open
26. 26.Which of these saves electricity? (a) run fans in empty rooms (b) unplug idle chargers (c) iron one shirt at a time (d) leave fridge door open
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 900 Ω resistor? (a) brown-white-brown (b) white-black-brown (c) white-black-black (d) white-black-red
28. 28.🔺 A 12.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
29. 29.🌈 In the resistor colour code, which number does violet stand for?
30. 30.🌈 A resistor has the colour bands violet, blue, red. What is its value (in ohms)?
31. 31.Which of these is measured in watts (W)? (a) power (b) resistance (c) current (d) voltage
32. 32.Which of these wastes electricity? (a) use LED lamps (b) set the AC to 24 °C (c) unplug idle chargers (d) iron one shirt at a time
33. 33.🌈 A resistor has the colour bands blue, blue, red. What is its value in kilo-ohms (kΩ)? =
34. 34.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
35. 35.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 ampere (c) 1 watt (d) 1 kilowatt-hour (kWh)
37. 37.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
38. 38.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 100 (c) 1000 (d) 1024
39. 39.🔺 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
40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 66 Ω resistor? (a) blue-violet-black (b) blue-blue-brown (c) violet-blue-black (d) blue-blue-black

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