Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 728 · 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 1.5 A. What is its power (in watts)? =
2. 2.⚡ A 2.4 W device works on 12 V. What current does it take (in amperes)? =
3. 3.True or false: voltage is measured in volts (V). (a) True (b) False
4. 4.True or false: resistance is measured in ohms (Ω). (a) True (b) False
5. 5.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
6. 6.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
7. 7.🧮 Resistors of 20 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
8. 8.Which of these wastes electricity? (a) set the AC to 24 °C (b) use daylight to read (c) iron one shirt at a time (d) switch off empty rooms
9. 9.🔺 A current of 1 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 45000 Ω resistor? (a) green-yellow-orange (b) yellow-green-yellow (c) yellow-green-red (d) yellow-green-orange
11. 11.🧩 Which component senses how bright it is? (a) motor (b) fuse (c) thermistor (d) LDR
12. 12.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V × I (d) R = V + I
13. 13.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
14. 14.💡 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?
15. 15.What does an LED do? (a) smooths a wobbly supply (b) is a resistance knob (c) has coloured bands (d) glows using little power
16. 16.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
17. 17.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the flow of water (c) a narrow pipe (d) the pipe colour
18. 18.📏 How many kilowatts (kW) is 2400 W? =
19. 19.🧩 Which component has coloured bands? (a) resistor (b) motor (c) LED (d) LDR
20. 20.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
21. 21.⚡ A 1.2 W device works on 12 V. What current does it take (in amperes)? =
22. 22.🔺 A current of 1.5 A flows when 9 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a diode (d) a buzzer
24. 24.📏 How many amperes (A) is 2620 mA? =
25. 25.True or false: the voltmeter measures current. (a) False (b) True
26. 26.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.What does a buzzer do? (a) limits the current (b) makes a beeping sound (c) lets current go one way (d) senses how bright it is
28. 28.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
29. 29.📏 How many kilowatts (kW) is 1350 W? =
30. 30.📏 How many amperes (A) is 2030 mA? =
31. 31.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
32. 32.True or false: a buzzer beeps for an alarm. (a) True (b) False
33. 33.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🧮 Resistors of 47 Ω, 22 Ω, 150 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
35. 35.💡 An LED is joined to a 5 V battery through a 220 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
36. 36.True or false: a resistor limits the current. (a) False (b) True
37. 37.🔍 Which is the odd one out? (a) leave the TV on standby (b) use old filament bulbs (c) use LED lamps (d) run fans in empty rooms
38. 38.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
39. 39.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
40. 40.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter

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