Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 200 · 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.📏 How many milliamperes (mA) is 0.53 A?
2. 2.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
3. 3.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
4. 4.🧩 Which component senses how hot it is? (a) potentiometer (b) resistor (c) thermistor (d) diode
5. 5.Which of these wastes electricity? (a) switch off empty rooms (b) set the AC to 24 °C (c) use LED lamps (d) leave the TV on standby
6. 6.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
7. 7.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I
8. 8.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
9. 9.Which of these is measured in amperes (A)? (a) voltage (b) how much a part resists (c) current (d) resistance
10. 10.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
11. 11.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
12. 12.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
13. 13.What does a resistor do? (a) is a resistance knob (b) senses how bright it is (c) has coloured bands (d) senses how hot it is
14. 14.🔺 A 3 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
15. 15.🔺 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
16. 16.🔺 A 3 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
17. 17.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
18. 18.🧩 Which component makes a beeping sound? (a) capacitor (b) buzzer (c) diode (d) potentiometer
19. 19.🔺 A current of 50 mA flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V × R (d) I = V ÷ R
21. 21.🔺 A current of 2 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
23. 23.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
24. 24.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water pressure (c) the tap handle (d) the water tank lid
25. 25.⚡ A device works on 9 V and takes 3 A. What is its power (in watts)? =
26. 26.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
27. 27.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
28. 28.⚡ A device works on 5 V and takes 1 A. What is its power (in watts)? =
29. 29.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light energy dial (d) light-emitting diode
30. 30.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
31. 31.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) the one nearest an end (d) any band
32. 32.True or false: a thermistor senses how hot it is. (a) True (b) False
33. 33.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🔺 A current of 1.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
35. 35.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
36. 36.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
37. 37.📏 How many milliamperes (mA) is 0.82 A?
38. 38.True or false: resistance is measured in amperes (A). (a) True (b) False
39. 39.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.True or false: voltage is measured in amperes (A). (a) True (b) False

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