Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 419 · 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 current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
2. 2.True or false: a motor makes things spin. (a) False (b) True
3. 3.🧮 A 2.8 V battery is joined to 2 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
4. 4.🌈 A resistor has the colour bands blue, blue, red. What is its value in kilo-ohms (kΩ)? =
5. 5.What does a buzzer do? (a) glows using little power (b) makes a beeping sound (c) blows if current is high (d) limits the current
6. 6.📏 How many kilowatts (kW) is 950 W? =
7. 7.What does a potentiometer do? (a) limits the current (b) blows if current is high (c) is a resistance knob (d) has coloured bands
8. 8.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a resistor (d) a diode
9. 9.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
10. 10.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) smaller (d) zero
11. 11.🌈 A resistor has the colour bands brown, orange, red. What is its value (in ohms)?
12. 12.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to change its colour (d) to limit the current
13. 13.🔺 A current of 0.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
14. 14.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) energy used each second (d) the size of a cell
16. 16.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
17. 17.True or false: the ammeter measures voltage. (a) False (b) True
18. 18.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
19. 19.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.True or false: how much a part resists is measured in ohms (Ω). (a) True (b) False
21. 21.What does an LED do? (a) glows using little power (b) boosts a small signal (c) senses how hot it is (d) makes a beeping sound
22. 22.💡 What does LED stand for? (a) light energy dial (b) light-emitting diode (c) low energy device (d) large electric dial
23. 23.🔺 A 15 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
24. 24.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
25. 25.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
26. 26.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.🌈 A resistor has the colour bands red, brown, red. What is its value (in ohms)?
28. 28.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an oil lamp (c) an LED lamp (d) a candle
29. 29.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🧩 Which component smooths a wobbly supply? (a) thermistor (b) resistor (c) potentiometer (d) capacitor
31. 31.⚡ A device works on 6 V and takes 2 A. What is its power (in watts)? =
32. 32.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
33. 33.True or false: a fuse blows if current is high. (a) False (b) True
34. 34.🌈 In the resistor colour code, which number does brown stand for?
35. 35.📏 How many kilo-ohms (kΩ) is 1200 Ω? =
36. 36.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
37. 37.Which of these wastes electricity? (a) use LED lamps (b) close the fridge quickly (c) use daylight to read (d) use old filament bulbs
38. 38.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
39. 39.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
40. 40.⚡ A device works on 9 V and takes 0.25 A. What is its power (in watts)? =

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