Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 504 · 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 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🔺 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
3. 3.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🧩 Which component limits the current? (a) potentiometer (b) resistor (c) transistor (d) motor
6. 6.📏 Which unit measures current? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
7. 7.⚡ 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
8. 8.True or false: to use old filament bulbs saves electricity. (a) False (b) True
9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %
10. 10.🌈 In the resistor colour code, which number does brown stand for?
11. 11.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
12. 12.🧮 A 10 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
13. 13.🧮 A 10 V battery is joined to 8 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
14. 14.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a motor (c) an LED (d) a fuse
15. 15.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
16. 16.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
17. 17.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
18. 18.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
19. 19.True or false: current is measured in ohms (Ω). (a) False (b) True
20. 20.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
21. 21.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V + R (d) I = V ÷ R
22. 22.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the widest gap (d) the gold band
23. 23.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🔺 A 24 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
25. 25.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it changes colour (d) it does not light
26. 26.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
27. 27.What does a potentiometer do? (a) beeps for an alarm (b) turns a fan or wheels (c) is a resistance knob (d) smooths a wobbly supply
28. 28.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
29. 29.🌈 A resistor has the colour bands red, brown, brown. What is its value (in ohms)?
30. 30.True or false: the voltmeter is joined in series. (a) False (b) True
31. 31.🧮 Resistors of 68 Ω, 20 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
32. 32.🧮 A 330 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
33. 33.True or false: a diode lets current go one way. (a) True (b) False
34. 34.🔺 A 4.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
35. 35.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
37. 37.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
38. 38.🔺 A 4.7 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
39. 39.🧮 Resistors of 10 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
40. 40.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)

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