Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 217 · 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.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a resistor (d) a buzzer
2. 2.📏 How many milliamperes (mA) is 0.2 A?
3. 3.🔺 A current of 25 mA flows when 5.5 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
5. 5.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🌈 In the resistor colour code, which number does brown stand for?
7. 7.Which of these wastes electricity? (a) use daylight to read (b) close the fridge quickly (c) leave fridge door open (d) use LED lamps
8. 8.🌈 A resistor has the colour bands brown, white, black. What is its value (in ohms)?
9. 9.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to limit the current (d) to make it brighter
10. 10.Which of these is measured in watts (W)? (a) current (b) resistance (c) how much a part resists (d) power
11. 11.🔍 Which is the odd one out? (a) close the fridge quickly (b) leave fridge door open (c) use old filament bulbs (d) leave the TV on standby
12. 12.What does a resistor do? (a) senses how hot it is (b) limits the current (c) makes a beeping sound (d) glows using little power
13. 13.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
14. 14.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 21000 Ω resistor? (a) red-brown-orange (b) red-brown-yellow (c) red-brown-red (d) brown-red-orange
17. 17.🌈 A resistor has the colour bands red, green, black. What is its value (in ohms)?
18. 18.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
19. 19.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) less than either one (d) more than either one
20. 20.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
21. 21.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
22. 22.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5000 Ω resistor? (a) green-black-red (b) green-black-brown (c) blue-green-red (d) green-black-orange
24. 24.🔺 A current of 1.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🔺 A current of 2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🧮 Resistors of 50 Ω, 50 Ω, 10 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
27. 27.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
28. 28.⚡ A device works on 1.5 V and takes 2 A. What is its power (in watts)? =
29. 29.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 56 Ω resistor? (a) green-blue-brown (b) blue-green-black (c) green-blue-black (d) blue-blue-black
31. 31.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
32. 32.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
33. 33.🧮 Resistors of 220 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
34. 34.🧩 Which component limits the current? (a) buzzer (b) LED (c) resistor (d) capacitor
35. 35.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
36. 36.🔺 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
37. 37.🌈 A resistor has the colour bands yellow, grey, orange. What is its value in kilo-ohms (kΩ)? =
38. 38.🧮 Resistors of 22 Ω, 22 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
39. 39.What does a capacitor do? (a) turns a fan or wheels (b) smooths a wobbly supply (c) makes things spin (d) is a resistance knob
40. 40.🧩 Which component smooths a wobbly supply? (a) fuse (b) capacitor (c) potentiometer (d) motor

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