Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 800 · 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 formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
2. 2.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
3. 3.🔺 A current of 50 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.📏 Which unit measures the flow of charge? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
5. 5.What does a thermistor do? (a) senses how hot it is (b) limits the current (c) makes things spin (d) glows using little power
6. 6.⚡ A 13.5 W device works on 9 V. What current does it take (in amperes)? =
7. 7.🌈 In the resistor colour code, which number does yellow stand for?
8. 8.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) a narrow pipe (c) the flow of water (d) the water pressure
9. 9.Which of these is measured in amperes (A)? (a) current (b) voltage (c) energy used each second (d) resistance
10. 10.⚡ 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
11. 11.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
12. 12.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
13. 13.Which of these is measured in watts (W)? (a) how much a part resists (b) resistance (c) power (d) current
14. 14.True or false: to use old filament bulbs saves electricity. (a) True (b) False
15. 15.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the pipe colour (c) the water tank lid (d) the water pressure
16. 16.What does an LED do? (a) glows using little power (b) makes things spin (c) senses how bright it is (d) blows if current is high
17. 17.True or false: current is measured in amperes (A). (a) True (b) False
18. 18.Which of these wastes electricity? (a) unplug idle chargers (b) iron one shirt at a time (c) use LED lamps (d) use daylight to read
19. 19.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
20. 20.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to change its colour (d) to make it brighter
21. 21.🔺 A current of 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🔍 Which is the odd one out? (a) unplug idle chargers (b) use LED lamps (c) set the AC to 24 °C (d) iron one shirt at a time
23. 23.🔺 A 10 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
24. 24.🌈 A resistor has the colour bands yellow, black, red. What is its value in kilo-ohms (kΩ)? =
25. 25.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 1000 (c) 10 (d) 100
26. 26.🧩 Which component senses how bright it is? (a) LDR (b) buzzer (c) capacitor (d) thermistor
27. 27.Which of these is measured in ohms (Ω)? (a) power (b) resistance (c) current (d) the push of a cell
28. 28.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end
29. 29.🌈 A resistor has the colour bands green, yellow, orange. What is its value (in ohms)?
30. 30.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
31. 31.🌈 In the resistor colour code, which number does white stand for?
32. 32.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
33. 33.True or false: the ammeter measures voltage. (a) False (b) True
34. 34.🔍 Which is the odd one out? (a) leave the TV on standby (b) leave fridge door open (c) switch off empty rooms (d) use old filament bulbs
35. 35.🔺 A current of 40 mA flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
36. 36.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
37. 37.⚡ A device works on 9 V and takes 0.1 A. What is its power (in watts)? =
38. 38.🔺 A 0.4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
39. 39.True or false: to switch off empty rooms wastes electricity. (a) True (b) False
40. 40.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =

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