Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 567 · 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 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) a filament bulb (d) an LED lamp
3. 3.🧩 Which component makes a beeping sound? (a) resistor (b) thermistor (c) diode (d) buzzer
4. 4.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
5. 5.True or false: how much a part resists is measured in watts (W). (a) False (b) True
6. 6.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
7. 7.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
8. 8.True or false: to use LED lamps saves electricity. (a) False (b) True
9. 9.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
10. 10.True or false: energy used each second is measured in watts (W). (a) True (b) False
11. 11.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.What does a transistor do? (a) stores a little charge (b) makes things spin (c) boosts a small signal (d) has coloured bands
13. 13.📏 How many amperes (A) is 1320 mA? =
14. 14.🧮 Resistors of 47 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
15. 15.True or false: an LED is a resistance knob. (a) False (b) True
16. 16.🔺 A 1 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
17. 17.⚡ A device works on 12 V and takes 2 A. What is its power (in watts)? =
18. 18.True or false: an LED turns a fan or wheels. (a) False (b) True
19. 19.True or false: how much a part resists is measured in volts (V). (a) False (b) True
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 930 Ω resistor? (a) white-orange-brown (b) orange-white-brown (c) white-orange-black (d) white-orange-red
21. 21.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) energy used each second (d) the length of a wire
22. 22.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🧮 Resistors of 220 Ω, 100 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
24. 24.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.💡 An LED is joined to a 5 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) does not light (c) lights up
26. 26.🧮 Resistors of 47 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
27. 27.🧩 Which component makes things spin? (a) buzzer (b) diode (c) motor (d) thermistor
28. 28.🌈 In the resistor colour code, which number does blue stand for?
29. 29.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
30. 30.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
32. 32.🔺 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
33. 33.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🔺 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
35. 35.True or false: current is measured in volts (V). (a) True (b) False
36. 36.🔺 A 20 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
37. 37.🌈 In the resistor colour code, which number does brown stand for?
38. 38.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer
40. 40.🔺 A current of 1 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?

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