Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 26 · 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 current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
2. 2.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the colour of light (d) the length of a wire
3. 3.🧩 Which component senses how bright it is? (a) diode (b) LDR (c) transistor (d) resistor
4. 4.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) store charge briefly (d) spin a wheel
5. 5.What does an LDR do? (a) smooths a wobbly supply (b) is a resistance knob (c) makes a beeping sound (d) senses how bright it is
6. 6.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
7. 7.🌈 A resistor has the colour bands red, violet, red. What is its value in kilo-ohms (kΩ)? =
8. 8.📏 Which unit measures power? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
9. 9.🔺 A current of 1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🌈 A resistor has the colour bands green, brown, brown. What is its value (in ohms)?
11. 11.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
12. 12.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
14. 14.Which of these is measured in amperes (A)? (a) how much a part resists (b) voltage (c) energy used each second (d) current
15. 15.True or false: to close the fridge quickly saves electricity. (a) False (b) True
16. 16.⚡ A device works on 3 V and takes 0.2 A. What is its power (in watts)? =
17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 2800 Ω resistor? (a) grey-red-red (b) red-grey-red (c) red-grey-brown (d) red-grey-orange
18. 18.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
19. 19.📏 How many milliamperes (mA) is 1.78 A?
20. 20.🧮 A 50 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
21. 21.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
22. 22.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.True or false: the ammeter is joined in series. (a) True (b) False
25. 25.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it does not light (c) it makes a sound (d) it lights brighter
27. 27.⚡ An 18 W device works on 12 V. What current does it take (in amperes)? =
28. 28.🧮 A 10 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
29. 29.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V ÷ I (d) R = V × I
30. 30.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🔺 A current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
33. 33.📏 Which unit measures current? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
34. 34.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) less than either one (d) more than either one
35. 35.Which of these wastes electricity? (a) unplug idle chargers (b) use LED lamps (c) run fans in empty rooms (d) use daylight to read
36. 36.🌈 In the resistor colour code, which number does yellow stand for?
37. 37.🌈 In the resistor colour code, which number does black stand for?
38. 38.🌈 A resistor has the colour bands brown, red, black. What is its value (in ohms)?
39. 39.💡 An LED is joined to a 9 V battery through a 1000 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
40. 40.🌈 In the resistor colour code, which number does violet stand for?

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