Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 516 · 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 formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
2. 2.🧩 Which component has coloured bands? (a) capacitor (b) resistor (c) motor (d) buzzer
3. 3.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) an LED lamp (d) a filament bulb
5. 5.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
6. 6.📏 How many milliamperes (mA) is 1.5 A?
7. 7.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) more than either one (d) always zero
9. 9.True or false: the ammeter is joined across a part. (a) False (b) True
10. 10.What does a buzzer do? (a) senses how bright it is (b) stores a little charge (c) turns a fan or wheels (d) makes a beeping sound
11. 11.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.📏 Which unit measures voltage? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
14. 14.🔺 A 1.2 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
15. 15.⚡ A 1.5 W device works on 1.5 V. What current does it take (in amperes)? =
16. 16.What does an LED do? (a) glows using little power (b) senses how hot it is (c) lets current go one way (d) boosts a small signal
17. 17.💡 An LED is joined to a 9 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
18. 18.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) zero (d) smaller
19. 19.🧾 A 2000 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
20. 20.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) low energy device (d) large electric dial
21. 21.📏 How many milliamperes (mA) is 2.22 A?
22. 22.True or false: the flow of charge is measured in volts (V). (a) False (b) True
23. 23.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) spin a wheel (d) measure heat
24. 24.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
25. 25.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V ÷ I (c) R = I ÷ V (d) R = V × I
26. 26.True or false: voltage is measured in volts (V). (a) False (b) True
27. 27.🔺 A current of 0.2 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.🧮 Resistors of 100 Ω, 220 Ω, 47 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
29. 29.🧮 Resistors of 47 Ω, 68 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
30. 30.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
31. 31.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
32. 32.🧮 A 1 V battery is joined to 2 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
33. 33.True or false: a motor turns a fan or wheels. (a) False (b) True
34. 34.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🧮 A 47 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)?
36. 36.🌈 In the resistor colour code, which number does red stand for?
37. 37.Which of these is measured in ohms (Ω)? (a) current (b) power (c) the flow of charge (d) resistance
38. 38.🔺 A 10 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
39. 39.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
40. 40.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it does not light (d) it lights brighter

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