Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 129 · 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.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to change its colour (d) to limit the current
2. 2.📏 Which unit measures how much a part resists? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
3. 3.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) light-emitting diode (d) low energy device
4. 4.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V ÷ I (c) R = V × I (d) R = I ÷ V
5. 5.🔺 A current of 1 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.🌈 A resistor has the colour bands brown, violet, black. What is its value (in ohms)?
7. 7.📏 How many kilo-ohms (kΩ) is 5500 Ω? =
8. 8.What does a thermistor do? (a) smooths a wobbly supply (b) is a resistance knob (c) beeps for an alarm (d) senses how hot it is
9. 9.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.Which of these saves electricity? (a) leave fridge door open (b) use old filament bulbs (c) run fans in empty rooms (d) unplug idle chargers
11. 11.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
12. 12.Which of these wastes electricity? (a) use LED lamps (b) set the AC to 24 °C (c) use old filament bulbs (d) unplug idle chargers
13. 13.🔺 A current of 0.1 A flows when 0.2 V is joined across a resistor. What is its resistance (in ohms)?
14. 14.🔺 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
15. 15.🧾 A family uses 80 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
16. 16.📏 How many milliamperes (mA) is 2.05 A?
17. 17.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) an oil lamp (d) a filament bulb
18. 18.True or false: a fuse blows if current is high. (a) True (b) False
19. 19.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
20. 20.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
21. 21.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it changes colour (d) it does not light
22. 22.🧮 A 10 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
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.📏 Which unit measures power? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
25. 25.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = V ÷ R (d) I = R ÷ V
26. 26.🔺 A current of 0.25 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🧮 Resistors of 33 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
28. 28.🌈 In the resistor colour code, which number does violet stand for?
29. 29.⚡ A device works on 9 V and takes 0.1 A. What is its power (in watts)? =
30. 30.🌈 A resistor has the colour bands green, black, yellow. What is its value in kilo-ohms (kΩ)? =
31. 31.🧮 A 0.9 V battery is joined to 4 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
32. 32.🔺 A 0.8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
33. 33.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
34. 34.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
35. 35.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🧾 A 250 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
37. 37.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
38. 38.🌈 A resistor has the colour bands red, red, orange. What is its value in kilo-ohms (kΩ)? =
39. 39.🔺 A current of 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.🌈 A resistor has the colour bands orange, grey, red. What is its value in kilo-ohms (kΩ)? =

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