Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 329 · 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 is the odd one out? (a) leave fridge door open (b) use LED lamps (c) leave the TV on standby (d) run fans in empty rooms
2. 2.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
3. 3.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🔺 A current of 0.1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
5. 5.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to limit the current (d) to make it brighter
6. 6.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light-emitting diode (d) light energy dial
7. 7.📏 How many amperes (A) is 1640 mA? =
8. 8.Which of these is measured in amperes (A)? (a) how much a part resists (b) energy used each second (c) current (d) the push of a cell
9. 9.🌈 A resistor has the colour bands brown, grey, black. What is its value (in ohms)?
10. 10.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 60 (c) 100 (d) 1000
11. 11.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
12. 12.True or false: the voltmeter is joined in series. (a) True (b) False
13. 13.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
16. 16.🧮 A 470 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
17. 17.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 25 % (d) 50 %
19. 19.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7100 Ω resistor? (a) violet-brown-orange (b) violet-brown-brown (c) brown-violet-red (d) violet-brown-red
21. 21.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
22. 22.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
23. 23.Which of these is measured in volts (V)? (a) the flow of charge (b) power (c) energy used each second (d) voltage
24. 24.🌈 In the resistor colour code, which number does green stand for?
25. 25.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
26. 26.📏 How many kilo-ohms (kΩ) is 8200 Ω? =
27. 27.🌈 A resistor has the colour bands orange, green, red. What is its value (in ohms)?
28. 28.What does a resistor do? (a) senses how bright it is (b) lets current go one way (c) boosts a small signal (d) has coloured bands
29. 29.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
30. 30.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
31. 31.What does a capacitor do? (a) blows if current is high (b) is a resistance knob (c) smooths a wobbly supply (d) turns a fan or wheels
32. 32.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
33. 33.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🌈 A resistor has the colour bands yellow, red, yellow. What is its value in kilo-ohms (kΩ)? =
35. 35.True or false: current is measured in watts (W). (a) True (b) False
36. 36.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
37. 37.📏 Which unit measures voltage? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
38. 38.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
39. 39.📏 How many watts (W) is 1.9 kW?
40. 40.🧮 Resistors of 50 Ω, 470 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?

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