Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 126 · 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.True or false: a diode senses how bright it is. (a) False (b) True
2. 2.📏 Which unit measures power? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
3. 3.⚡ A 3 W device works on 12 V. What current does it take (in amperes)? =
4. 4.🔺 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
5. 5.🌈 A resistor has the colour bands orange, red, black. What is its value (in ohms)?
6. 6.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) an oil lamp (d) a filament bulb
7. 7.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
8. 8.What does a diode do? (a) makes a beeping sound (b) lets current go one way (c) is a resistance knob (d) stores a little charge
9. 9.🔺 A current of 25 mA flows when 5.5 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.🧮 Resistors of 50 Ω, 50 Ω, 330 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.True or false: a transistor has coloured bands. (a) True (b) False
12. 12.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🧾 A 250 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
14. 14.What does a capacitor do? (a) glows using little power (b) turns a fan or wheels (c) smooths a wobbly supply (d) is a resistance knob
15. 15.🔺 An 8 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
16. 16.🔺 A 20 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
17. 17.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
19. 19.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
20. 20.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
21. 21.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
22. 22.🔺 A current of 1.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
24. 24.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
25. 25.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
27. 27.💡 What happens if an LED is put in backwards? (a) it does not light (b) it lights brighter (c) it changes colour (d) it makes a sound
28. 28.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) their sum (d) less than either one
29. 29.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
30. 30.Which of these is measured in ohms (Ω)? (a) current (b) resistance (c) the push of a cell (d) power
31. 31.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
32. 32.⚡ A 1.5 W device works on 6 V. What current does it take (in amperes)? =
33. 33.Which of these saves electricity? (a) iron one shirt at a time (b) run fans in empty rooms (c) use LED lamps (d) leave fridge door open
34. 34.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
35. 35.🧮 A 100 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
36. 36.🌈 A resistor has the colour bands brown, white, red. What is its value in kilo-ohms (kΩ)? =
37. 37.🔺 A current of 3 A flows when 45 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a motor (d) a fuse
39. 39.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 33 Ω resistor? (a) orange-orange-black (b) orange-yellow-black (c) orange-orange-brown (d) yellow-orange-black
40. 40.🔺 A 4 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?

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