Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 359 · 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 device works on 12 V and takes 0.5 A. What is its power (in watts)? =
2. 2.📏 Which unit measures resistance? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
3. 3.🧮 A 2 V battery is joined to 8 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
4. 4.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) less than either one (d) their sum
5. 5.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🌈 In the resistor colour code, which number does white stand for?
7. 7.True or false: the ammeter is joined across a part. (a) True (b) False
8. 8.🧮 Resistors of 50 Ω, 150 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
9. 9.🧮 Resistors of 150 Ω, 47 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
10. 10.🌈 A resistor has the colour bands blue, grey, orange. What is its value (in ohms)?
11. 11.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
12. 12.Which of these is measured in watts (W)? (a) how much a part resists (b) the flow of charge (c) current (d) energy used each second
13. 13.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 10 (c) 100 (d) 1024
14. 14.Which of these is measured in ohms (Ω)? (a) current (b) resistance (c) voltage (d) power
15. 15.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
16. 16.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🌈 A resistor has the colour bands white, yellow, orange. What is its value (in ohms)?
18. 18.🔺 A 15 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
19. 19.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
20. 20.⚡ A 72 W device works on 24 V. What current does it take (in amperes)? =
21. 21.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
23. 23.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
24. 24.What does a transistor do? (a) makes a beeping sound (b) boosts a small signal (c) lets current go one way (d) turns a fan or wheels
25. 25.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
26. 26.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔺 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
28. 28.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) a motor (d) an LED
29. 29.🔺 A 15 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
30. 30.⚡ A 2.4 W device works on 12 V. What current does it take (in amperes)? =
31. 31.True or false: a capacitor smooths a wobbly supply. (a) True (b) False
32. 32.Which of these wastes electricity? (a) use daylight to read (b) use LED lamps (c) leave fridge door open (d) switch off empty rooms
33. 33.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) an LED lamp (d) a filament bulb
34. 34.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.💡 A red LED uses 2 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
36. 36.What does a diode do? (a) senses how bright it is (b) has coloured bands (c) lets current go one way (d) smooths a wobbly supply
37. 37.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
38. 38.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
39. 39.True or false: a fuse blows if current is high. (a) False (b) True
40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 73000 Ω resistor? (a) orange-violet-orange (b) violet-orange-red (c) violet-orange-yellow (d) violet-orange-orange

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