Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 841 · 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 current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
3. 3.📏 How many amperes (A) is 1910 mA? =
4. 4.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
5. 5.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
6. 6.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 watt
7. 7.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
8. 8.🧩 Which component blows if current is high? (a) transistor (b) LDR (c) fuse (d) motor
9. 9.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.🧮 A 100 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
12. 12.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
13. 13.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
14. 14.⚡ A 2.25 W device works on 9 V. What current does it take (in amperes)? =
15. 15.🧮 Resistors of 22 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
16. 16.True or false: to switch off empty rooms saves electricity. (a) True (b) False
17. 17.🌈 A resistor has the colour bands red, brown, yellow. What is its value in kilo-ohms (kΩ)? =
18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 870 Ω resistor? (a) grey-violet-brown (b) violet-grey-brown (c) grey-violet-black (d) grey-violet-red
19. 19.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
20. 20.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.🌈 A resistor has the colour bands green, blue, brown. What is its value (in ohms)?
22. 22.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
23. 23.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
24. 24.True or false: to switch off empty rooms wastes electricity. (a) True (b) False
25. 25.True or false: a diode is a resistance knob. (a) False (b) True
26. 26.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.True or false: the ammeter is joined across a part. (a) True (b) False
28. 28.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) measure heat (d) store charge briefly
29. 29.🌈 A resistor has the colour bands grey, yellow, yellow. What is its value in kilo-ohms (kΩ)? =
30. 30.Which of these saves electricity? (a) unplug idle chargers (b) leave the TV on standby (c) leave fridge door open (d) run fans in empty rooms
31. 31.🔺 A 7.5 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
32. 32.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
33. 33.🔺 A current of 0.25 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🌈 A resistor has the colour bands grey, red, yellow. What is its value in kilo-ohms (kΩ)? =
35. 35.🧾 A 50 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
36. 36.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
37. 37.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) light energy dial (d) low energy device
38. 38.What does a resistor do? (a) boosts a small signal (b) beeps for an alarm (c) limits the current (d) senses how hot it is
39. 39.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
40. 40.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)

Free electronics lessons, practice and worksheets at talentjr.in/electronics-for-kids