Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 786 · 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.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
2. 2.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
3. 3.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
4. 4.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I + R (c) V = I ÷ R (d) V = R ÷ I
6. 6.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) spin a wheel (d) store charge briefly
7. 7.🧮 A 0.8 V battery is joined to 5 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
8. 8.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
9. 9.What does a buzzer do? (a) makes a beeping sound (b) is a resistance knob (c) lets current go one way (d) senses how bright it is
10. 10.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.Which of these wastes electricity? (a) use daylight to read (b) unplug idle chargers (c) switch off empty rooms (d) run fans in empty rooms
12. 12.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
13. 13.🌈 A resistor has the colour bands grey, grey, black. What is its value (in ohms)?
14. 14.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
15. 15.📏 How many amperes (A) is 2480 mA? =
16. 16.Which of these is measured in volts (V)? (a) current (b) voltage (c) the flow of charge (d) energy used each second
17. 17.What does a fuse do? (a) beeps for an alarm (b) turns a fan or wheels (c) limits the current (d) blows if current is high
18. 18.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell
19. 19.📏 How many amperes (A) is 490 mA? =
20. 20.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
21. 21.📏 Which unit measures the flow of charge? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
22. 22.📏 How many kilowatts (kW) is 4500 W? =
23. 23.True or false: the voltmeter is joined in series. (a) True (b) False
24. 24.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
25. 25.True or false: the ammeter measures voltage. (a) True (b) False
26. 26.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) becomes zero (d) gets bigger
27. 27.🧾 A family uses 70 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
28. 28.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
29. 29.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
30. 30.📏 How many kilo-ohms (kΩ) is 1400 Ω? =
31. 31.🔺 A current of 2.5 A flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
33. 33.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an oil lamp (d) an LED lamp
34. 34.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
36. 36.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it changes colour (d) it does not light
37. 37.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.🧮 Resistors of 100 Ω, 22 Ω, 68 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
39. 39.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =

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