Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 430 · 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.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) does not light (c) may burn out
2. 2.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
4. 4.True or false: the voltmeter is joined in series. (a) True (b) False
5. 5.What does a resistor do? (a) smooths a wobbly supply (b) has coloured bands (c) lets current go one way (d) is a resistance knob
6. 6.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
7. 7.🔺 A 2 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
8. 8.🧮 Resistors of 470 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
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 7 hours. How many watt-hours (Wh) are saved?
10. 10.True or false: to use daylight to read saves electricity. (a) False (b) True
11. 11.🌈 A resistor has the colour bands grey, grey, orange. What is its value (in ohms)?
12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
13. 13.🧮 Resistors of 100 Ω, 100 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
14. 14.🌈 A resistor has the colour bands brown, black, yellow. What is its value in kilo-ohms (kΩ)? =
15. 15.True or false: a transistor boosts a small signal. (a) False (b) True
16. 16.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
17. 17.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
18. 18.🧮 Resistors of 47 Ω, 22 Ω, 33 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
19. 19.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8300 Ω resistor? (a) orange-grey-red (b) grey-orange-orange (c) grey-orange-brown (d) grey-orange-red
20. 20.⚡ A 10 W device works on 5 V. What current does it take (in amperes)? =
21. 21.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
22. 22.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water pressure (c) the water tank lid (d) the tap handle
23. 23.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
27. 27.🌈 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
28. 28.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
29. 29.🌈 A resistor has the colour bands orange, blue, yellow. What is its value in kilo-ohms (kΩ)? =
30. 30.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
31. 31.📏 How many watts (W) is 0.1 kW?
32. 32.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🧮 A 3.2 V battery is joined to 10 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
34. 34.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
35. 35.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
36. 36.🔺 A current of 0.1 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🌈 In the resistor colour code, which number does brown stand for?
38. 38.🌈 A resistor has the colour bands grey, black, brown. What is its value (in ohms)?
39. 39.📏 Which unit measures voltage? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
40. 40.True or false: a resistor lets current go one way. (a) True (b) False

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