Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 737 · 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.What does a motor do? (a) lets current go one way (b) blows if current is high (c) stores a little charge (d) turns a fan or wheels
2. 2.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) zero (d) stay the same
3. 3.🌈 In the resistor colour code, which number does brown stand for?
4. 4.True or false: a resistor has coloured bands. (a) True (b) False
5. 5.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
6. 6.🧮 Resistors of 150 Ω, 330 Ω, 470 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
7. 7.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
8. 8.What does an LED do? (a) limits the current (b) glows using little power (c) senses how bright it is (d) has coloured bands
9. 9.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
10. 10.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) low energy device (d) light energy dial
11. 11.True or false: energy used each second is measured in watts (W). (a) False (b) True
12. 12.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
14. 14.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
15. 15.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
16. 16.🔍 Which is the odd one out? (a) switch off empty rooms (b) use LED lamps (c) use daylight to read (d) leave fridge door open
17. 17.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
18. 18.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
19. 19.📏 Which unit measures how much a part resists? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
20. 20.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an oil lamp (d) an LED lamp
21. 21.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
22. 22.True or false: a fuse makes things spin. (a) False (b) True
23. 23.🌈 A resistor has the colour bands white, red, yellow. What is its value in kilo-ohms (kΩ)? =
24. 24.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
25. 25.True or false: the ammeter measures voltage. (a) True (b) False
26. 26.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
27. 27.🧾 A 500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
28. 28.🌈 A resistor has the colour bands yellow, yellow, brown. What is its value (in ohms)?
29. 29.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
30. 30.🧩 Which component limits the current? (a) diode (b) transistor (c) LDR (d) resistor
31. 31.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a capacitor (d) a buzzer
32. 32.True or false: the ammeter is joined across a part. (a) False (b) True
33. 33.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
34. 34.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
36. 36.🔺 A 1.2 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
37. 37.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
38. 38.What does a diode do? (a) blows if current is high (b) lets current go one way (c) glows using little power (d) makes things spin
39. 39.True or false: a resistor makes things spin. (a) True (b) False
40. 40.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to store charge (d) to limit the current

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