Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 315 · 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 10 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
2. 2.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
3. 3.Which of these is measured in amperes (A)? (a) energy used each second (b) the push of a cell (c) current (d) power
4. 4.What does a motor do? (a) makes a beeping sound (b) blows if current is high (c) is a resistance knob (d) makes things spin
5. 5.🌈 A resistor has the colour bands brown, green, black. What is its value (in ohms)?
6. 6.🧩 Which component makes a beeping sound? (a) transistor (b) resistor (c) buzzer (d) LED
7. 7.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🔍 Which is the odd one out? (a) use old filament bulbs (b) unplug idle chargers (c) switch off empty rooms (d) set the AC to 24 °C
9. 9.⚡ A 12 W device works on 12 V. What current does it take (in amperes)? =
10. 10.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
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.🧮 A 220 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
14. 14.📏 Which unit measures the flow of charge? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
15. 15.True or false: an LED stores a little charge. (a) False (b) True
16. 16.📏 How many milliamperes (mA) is 1.2 A?
17. 17.🌈 A resistor has the colour bands orange, red, orange. What is its value (in ohms)?
18. 18.🧮 A 68 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
19. 19.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 71 Ω resistor? (a) violet-brown-brown (b) violet-brown-black (c) brown-violet-black (d) grey-brown-black
21. 21.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🔺 A current of 2.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A current of 10 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.Which of these is measured in amperes (A)? (a) energy used each second (b) the flow of charge (c) power (d) the push of a cell
25. 25.🔺 A current of 2.5 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.Which of these is measured in watts (W)? (a) current (b) voltage (c) power (d) how much a part resists
27. 27.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
28. 28.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to make it brighter (c) to store charge (d) to limit the current
29. 29.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
30. 30.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
31. 31.True or false: current is measured in amperes (A). (a) True (b) False
32. 32.📏 How many watts (W) is 1.6 kW?
33. 33.True or false: the push of a cell is measured in ohms (Ω). (a) True (b) False
34. 34.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
35. 35.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
36. 36.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) does not light (c) lights up
37. 37.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
38. 38.What does a motor do? (a) smooths a wobbly supply (b) turns a fan or wheels (c) limits the current (d) senses how hot it is
39. 39.What does a fuse do? (a) blows if current is high (b) makes things spin (c) smooths a wobbly supply (d) is a resistance knob
40. 40.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I

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