Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 597 · 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 gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 0 % (d) 25 %
2. 2.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
3. 3.🔺 A current of 20 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.🔺 A 20 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
5. 5.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) a bigger tank (c) the flow of water (d) a narrow pipe
6. 6.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
7. 7.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = V + I (d) R = I ÷ V
8. 8.🌈 A resistor has the colour bands violet, black, orange. What is its value (in ohms)?
9. 9.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
10. 10.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
11. 11.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
12. 12.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
13. 13.What does a diode do? (a) smooths a wobbly supply (b) makes a beeping sound (c) blows if current is high (d) lets current go one way
14. 14.🧾 A 200 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
15. 15.True or false: a resistor senses how bright it is. (a) False (b) True
16. 16.🌈 A resistor has the colour bands red, violet, red. What is its value in kilo-ohms (kΩ)? =
17. 17.🔺 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
18. 18.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
19. 19.Which of these saves electricity? (a) leave fridge door open (b) run fans in empty rooms (c) switch off empty rooms (d) iron one shirt at a time
20. 20.Which of these wastes electricity? (a) unplug idle chargers (b) use daylight to read (c) use old filament bulbs (d) set the AC to 24 °C
21. 21.🌈 In the resistor colour code, which number does grey stand for?
22. 22.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
23. 23.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
24. 24.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a capacitor (d) a diode
25. 25.📏 Which unit measures voltage? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
26. 26.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
27. 27.🧮 Resistors of 22 Ω, 470 Ω, 330 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
28. 28.🧮 A 3.5 V battery is joined to 4 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
29. 29.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) the gold band (d) any band
30. 30.⚡ A 1.5 W device works on 6 V. What current does it take (in amperes)? =
31. 31.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) measure heat (d) spin a wheel
32. 32.🧩 Which component beeps for an alarm? (a) fuse (b) transistor (c) buzzer (d) capacitor
33. 33.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
34. 34.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
35. 35.🌈 A resistor has the colour bands violet, black, brown. What is its value (in ohms)?
36. 36.🌈 A resistor has the colour bands green, black, red. What is its value (in ohms)?
37. 37.📏 How many watts (W) is 0.6 kW?
38. 38.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
39. 39.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
40. 40.🔍 Which is the odd one out? (a) run fans in empty rooms (b) use daylight to read (c) use LED lamps (d) switch off empty rooms

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