Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 222 · 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 3 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
2. 2.What does a diode do? (a) senses how bright it is (b) has coloured bands (c) lets current go one way (d) smooths a wobbly supply
3. 3.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
4. 4.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
5. 5.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
6. 6.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.Which of these saves electricity? (a) iron one shirt at a time (b) leave the TV on standby (c) set the AC to 24 °C (d) use old filament bulbs
8. 8.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
9. 9.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
10. 10.🌈 In the resistor colour code, which number does black stand for?
11. 11.📏 How many watts (W) is 0.2 kW?
12. 12.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
13. 13.🧩 Which component stores a little charge? (a) transistor (b) diode (c) capacitor (d) fuse
14. 14.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
15. 15.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = R ÷ V (d) I = V ÷ R
16. 16.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to make it brighter (d) to store charge
17. 17.🧮 A 5 V battery is joined to 2 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
18. 18.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
19. 19.🌈 In the resistor colour code, which number does grey stand for?
20. 20.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🧮 Resistors of 330 Ω, 330 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
22. 22.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
24. 24.⚡ 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
25. 25.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I + R (d) V = I ÷ R
27. 27.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 2000 Ω resistor? (a) red-black-orange (b) orange-red-red (c) red-black-brown (d) red-black-red
29. 29.📏 How many ohms (Ω) is 8.9 kΩ?
30. 30.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
31. 31.⚡ A 6 W device works on 24 V. What current does it take (in amperes)? =
32. 32.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) a resistor (d) an LED
33. 33.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
34. 34.True or false: to use old filament bulbs saves electricity. (a) False (b) True
35. 35.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
36. 36.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
37. 37.🌈 In the resistor colour code, which number does orange stand for?
38. 38.🌈 A resistor has the colour bands blue, grey, black. What is its value (in ohms)?
39. 39.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
40. 40.True or false: a buzzer beeps for an alarm. (a) False (b) True

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