Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 334 · 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 device works on 6 V and takes 3 A. What is its power (in watts)? =
2. 2.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
3. 3.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🧩 Which part changes electrical energy into movement? (a) a motor (b) a resistor (c) an LED (d) a fuse
5. 5.Which of these is measured in amperes (A)? (a) power (b) current (c) resistance (d) how much a part resists
6. 6.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 45000 Ω resistor? (a) green-yellow-orange (b) yellow-green-orange (c) yellow-green-red (d) yellow-green-yellow
8. 8.🌈 A resistor has the colour bands orange, yellow, red. What is its value (in ohms)?
9. 9.🔺 A 5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
10. 10.💡 What does LED stand for? (a) light-emitting diode (b) low energy device (c) light energy dial (d) large electric dial
11. 11.🌈 A resistor has the colour bands brown, black, red. What is its value in kilo-ohms (kΩ)? =
12. 12.📏 How many kilowatts (kW) is 1350 W? =
13. 13.🧾 A 1000 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
14. 14.Which of these saves electricity? (a) iron one shirt at a time (b) leave the TV on standby (c) use old filament bulbs (d) use LED lamps
15. 15.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
16. 16.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to change its colour (d) to make it brighter
17. 17.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a diode (d) a resistor
18. 18.What does an LDR do? (a) senses how hot it is (b) turns a fan or wheels (c) senses how bright it is (d) stores a little charge
19. 19.True or false: to run fans in empty rooms saves electricity. (a) False (b) True
20. 20.🔍 Which is the odd one out? (a) leave fridge door open (b) switch off empty rooms (c) set the AC to 24 °C (d) close the fridge quickly
21. 21.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
22. 22.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
23. 23.🧾 A family uses 190 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
24. 24.🔺 A current of 40 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
25. 25.🌈 A resistor has the colour bands green, grey, red. What is its value (in ohms)?
26. 26.💡 A red LED uses 2 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
27. 27.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
28. 28.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
29. 29.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
30. 30.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
31. 31.⚡ An 18 W device works on 9 V. What current does it take (in amperes)? =
32. 32.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
33. 33.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🧩 Which component smooths a wobbly supply? (a) capacitor (b) LED (c) LDR (d) fuse
36. 36.💡 An LED is joined to a 6 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
37. 37.🌈 A resistor has the colour bands red, blue, brown. What is its value (in ohms)?
38. 38.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
39. 39.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
40. 40.True or false: to set the AC to 24 °C wastes electricity. (a) False (b) True

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