Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 940 · 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.🧮 Resistors of 330 Ω, 150 Ω, 50 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
2. 2.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) large electric dial (d) low energy device
3. 3.📏 How many milliamperes (mA) is 2.6 A?
4. 4.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %
5. 5.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
6. 6.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
7. 7.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
8. 8.📏 How many kilo-ohms (kΩ) is 4200 Ω? =
9. 9.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
10. 10.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 56000 Ω resistor? (a) green-blue-yellow (b) green-blue-orange (c) blue-green-orange (d) green-blue-red
12. 12.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
14. 14.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🔺 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
16. 16.True or false: a buzzer boosts a small signal. (a) False (b) True
17. 17.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
18. 18.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
19. 19.📏 How many kilowatts (kW) is 3400 W? =
20. 20.True or false: to unplug idle chargers wastes electricity. (a) True (b) False
21. 21.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
22. 22.🧮 A 330 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)?
23. 23.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
24. 24.🧾 A 250 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
25. 25.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) any band (d) the gold band
26. 26.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
28. 28.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 60 (c) 1000 (d) 10
29. 29.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
30. 30.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
31. 31.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
32. 32.⚡ A device works on 5 V and takes 0.1 A. What is its power (in watts)? =
33. 33.🔺 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
34. 34.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) zero (d) smaller
35. 35.What does a resistor do? (a) makes things spin (b) limits the current (c) senses how hot it is (d) stores a little charge
36. 36.🧮 A 50 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)?
37. 37.🧮 Resistors of 470 Ω, 20 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
38. 38.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
39. 39.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) an LED lamp (c) a filament bulb (d) a candle
40. 40.🌈 A resistor has the colour bands red, violet, red. What is its value (in ohms)?

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