Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 519 · 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.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
2. 2.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
3. 3.🔺 A 9 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
4. 4.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1500 Ω resistor? (a) brown-green-brown (b) brown-green-orange (c) brown-green-red (d) green-brown-red
5. 5.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
6. 6.Which of these is measured in ohms (Ω)? (a) energy used each second (b) power (c) resistance (d) the flow of charge
7. 7.True or false: to use daylight to read saves electricity. (a) True (b) False
8. 8.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I ÷ R (d) V = I + R
9. 9.🔺 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
10. 10.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
11. 11.🌈 A resistor has the colour bands green, orange, red. What is its value in kilo-ohms (kΩ)? =
12. 12.📏 Which unit measures the push of a cell? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
13. 13.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🌈 In the resistor colour code, which number does blue stand for?
15. 15.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to store charge (d) to limit the current
16. 16.True or false: to use LED lamps saves electricity. (a) True (b) False
17. 17.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) zero (d) stay the same
18. 18.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
19. 19.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
20. 20.Which of these is measured in watts (W)? (a) the flow of charge (b) voltage (c) resistance (d) energy used each second
21. 21.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light energy dial (d) light-emitting diode
22. 22.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
23. 23.True or false: a buzzer makes a beeping sound. (a) True (b) False
24. 24.📏 How many kilo-ohms (kΩ) is 6700 Ω? =
25. 25.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
26. 26.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = R ÷ V (d) I = V ÷ R
27. 27.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
28. 28.🔺 A current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the one nearest an end (d) the gold band
31. 31.🔺 A 15 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
32. 32.📏 How many ohms (Ω) is 5.9 kΩ?
33. 33.🔺 A 25 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
34. 34.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
35. 35.What does a potentiometer do? (a) senses how bright it is (b) is a resistance knob (c) lets current go one way (d) stores a little charge
36. 36.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🌈 A resistor has the colour bands white, red, brown. What is its value (in ohms)?
38. 38.Which of these saves electricity? (a) switch off empty rooms (b) iron one shirt at a time (c) use old filament bulbs (d) leave the TV on standby
39. 39.⚡ 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
40. 40.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) an LED (d) a motor

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