Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 415 · 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.True or false: to use old filament bulbs wastes electricity. (a) True (b) False
2. 2.True or false: to iron one shirt at a time wastes electricity. (a) False (b) True
3. 3.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
4. 4.🌈 In the resistor colour code, which number does blue stand for?
5. 5.⚡ A device works on 5 V and takes 2 A. What is its power (in watts)? =
6. 6.🧮 A 2.8 V battery is joined to 8 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
7. 7.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) an LED (d) a motor
8. 8.🧮 Resistors of 50 Ω, 100 Ω, 330 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
9. 9.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.Which of these wastes electricity? (a) use LED lamps (b) leave fridge door open (c) switch off empty rooms (d) use daylight to read
11. 11.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
12. 12.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
13. 13.⚡ A 3 W device works on 1.5 V. What current does it take (in amperes)? =
14. 14.True or false: resistance is measured in volts (V). (a) False (b) True
15. 15.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) store charge briefly (d) measure heat
16. 16.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
17. 17.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
18. 18.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 100 (d) 1000
19. 19.🔺 A current of 0.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
20. 20.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
21. 21.🌈 A resistor has the colour bands green, red, black. What is its value (in ohms)?
22. 22.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
23. 23.🔺 A current of 20 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
24. 24.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
25. 25.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the pipe colour (c) the water tank lid (d) the tap handle
26. 26.True or false: the ammeter measures current. (a) True (b) False
27. 27.🌈 In the resistor colour code, which number does brown stand for?
28. 28.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
29. 29.📏 How many watts (W) is 0.4 kW?
30. 30.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
31. 31.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
32. 32.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
33. 33.🔺 A current of 0.2 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
36. 36.What does a potentiometer do? (a) glows using little power (b) stores a little charge (c) turns a fan or wheels (d) is a resistance knob
37. 37.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the flow of water (c) the water pressure (d) the pipe colour
38. 38.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.Which of these is measured in amperes (A)? (a) how much a part resists (b) power (c) energy used each second (d) the flow of charge
40. 40.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a resistor (d) a diode

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