Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 136 · 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 capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
2. 2.🧩 Which component makes a beeping sound? (a) capacitor (b) buzzer (c) resistor (d) LDR
3. 3.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
4. 4.🌈 In the resistor colour code, which number does yellow stand for?
5. 5.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
6. 6.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
7. 7.🧮 Resistors of 50 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
8. 8.What does a capacitor do? (a) boosts a small signal (b) senses how hot it is (c) smooths a wobbly supply (d) makes things spin
9. 9.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
10. 10.🔺 A 37.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
11. 11.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = I ÷ V (c) R = V × I (d) R = V ÷ I
13. 13.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
14. 14.🧮 Resistors of 150 Ω, 50 Ω, 22 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
15. 15.💡 An LED is joined to a 3 V battery through a 470 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
16. 16.🌈 A resistor has the colour bands red, violet, brown. What is its value (in ohms)?
17. 17.🧾 A 500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
18. 18.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
19. 19.⚡ A 3 W device works on 12 V. What current does it take (in amperes)? =
20. 20.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
21. 21.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) the colour of light (d) energy used each second
22. 22.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A current of 3 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🔺 A current of 0.25 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
25. 25.True or false: an LED glows using little power. (a) True (b) False
26. 26.True or false: an LDR smooths a wobbly supply. (a) True (b) False
27. 27.True or false: how much a part resists is measured in volts (V). (a) True (b) False
28. 28.📏 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
29. 29.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to limit the current (d) to store charge
30. 30.💡 An LED is joined to a 9 V battery with no 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
31. 31.What does a potentiometer do? (a) beeps for an alarm (b) is a resistance knob (c) stores a little charge (d) glows using little power
32. 32.Which of these is measured in watts (W)? (a) the flow of charge (b) current (c) resistance (d) energy used each second
33. 33.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
34. 34.🧮 A 1.4 V battery is joined to 6 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
35. 35.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🧮 Resistors of 10 Ω, 47 Ω, 22 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.True or false: the flow of charge is measured in watts (W). (a) True (b) False
38. 38.🧮 An 8 V battery is joined to 10 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
39. 39.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I ÷ R (d) V = I × R
40. 40.True or false: the voltmeter measures voltage. (a) True (b) False

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