Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 436 · 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 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
2. 2.🔺 A current of 2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🌈 In the resistor colour code, which number does red stand for?
4. 4.🧾 A family uses 190 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
5. 5.📏 How many kilo-ohms (kΩ) is 4800 Ω? =
6. 6.🌈 A resistor has the colour bands orange, brown, orange. What is its value (in ohms)?
7. 7.🔺 A current of 20 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.Which of these wastes electricity? (a) close the fridge quickly (b) leave the TV on standby (c) set the AC to 24 °C (d) unplug idle chargers
9. 9.🔺 A 6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
10. 10.True or false: to use daylight to read saves electricity. (a) False (b) True
11. 11.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
12. 12.🌈 A resistor has the colour bands yellow, violet, red. What is its value (in ohms)?
13. 13.True or false: to switch off empty rooms saves electricity. (a) True (b) False
14. 14.⚡ A device works on 12 V and takes 2 A. What is its power (in watts)? =
15. 15.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) current (c) resistance (d) energy used each second
16. 16.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
17. 17.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) a candle (d) an oil lamp
18. 18.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
19. 19.🧮 Resistors of 330 Ω, 22 Ω, 150 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
20. 20.True or false: a buzzer stores a little charge. (a) False (b) True
21. 21.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
23. 23.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
24. 24.True or false: a transistor boosts a small signal. (a) False (b) True
25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 50 % (d) 0 %
26. 26.🌈 In the resistor colour code, which number does grey stand for?
27. 27.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
28. 28.What does a buzzer do? (a) has coloured bands (b) is a resistance knob (c) beeps for an alarm (d) blows if current is high
29. 29.💡 An LED is joined to a 12 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
30. 30.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
31. 31.Which of these wastes electricity? (a) switch off empty rooms (b) use daylight to read (c) iron one shirt at a time (d) use LED lamps
32. 32.⚡ A 6 W device works on 6 V. What current does it take (in amperes)? =
33. 33.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
34. 34.🧮 Resistors of 10 Ω, 330 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 13 Ω resistor? (a) red-orange-black (b) orange-brown-black (c) brown-orange-brown (d) brown-orange-black
36. 36.⚡ A 2.4 W device works on 12 V. What current does it take (in amperes)? =
37. 37.📏 How many ohms (Ω) is 0.7 kΩ?
38. 38.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
39. 39.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
40. 40.⚡ A 4.5 W device works on 9 V. What current does it take (in amperes)? =

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