Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 511 · 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 = I ÷ V (c) P = V × I (d) P = V ÷ I
2. 2.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
3. 3.True or false: the flow of charge is measured in ohms (Ω). (a) False (b) True
4. 4.🔺 A current of 25 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
6. 6.🧮 A 6 V battery is joined to 12 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
7. 7.🧩 Which component boosts a small signal? (a) fuse (b) LED (c) diode (d) transistor
8. 8.True or false: voltage is measured in amperes (A). (a) False (b) True
9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
10. 10.🧩 Which component makes a beeping sound? (a) thermistor (b) LED (c) motor (d) buzzer
11. 11.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 100 (c) 10 (d) 1000
12. 12.🌈 A resistor has the colour bands white, brown, brown. What is its value (in ohms)?
13. 13.🌈 A resistor has the colour bands grey, green, orange. What is its value (in ohms)?
14. 14.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
16. 16.🧩 Which component turns a fan or wheels? (a) motor (b) LED (c) resistor (d) thermistor
17. 17.True or false: a buzzer beeps for an alarm. (a) True (b) False
18. 18.Which of these wastes electricity? (a) set the AC to 24 °C (b) close the fridge quickly (c) use LED lamps (d) leave the TV on standby
19. 19.True or false: a resistor stores a little charge. (a) True (b) False
20. 20.💡 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
21. 21.🧮 A 330 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
22. 22.True or false: the voltmeter measures voltage. (a) True (b) False
23. 23.True or false: the ammeter is joined in series. (a) True (b) False
24. 24.📏 How many amperes (A) is 90 mA? =
25. 25.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) energy used each second (d) the length of a wire
26. 26.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
27. 27.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
28. 28.⚡ A 72 W device works on 24 V. What current does it take (in amperes)? =
29. 29.🔍 Which is the odd one out? (a) use daylight to read (b) switch off empty rooms (c) leave the TV on standby (d) use LED lamps
30. 30.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
31. 31.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) the pipe colour (c) the water pressure (d) a narrow pipe
32. 32.🌈 In the resistor colour code, which number does orange stand for?
33. 33.🧮 A 20 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
34. 34.🔺 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
35. 35.🔺 A current of 1.5 A flows when 4.5 V is joined across a resistor. What is its resistance (in ohms)?
36. 36.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
38. 38.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 4.25 V supply. What current flows (in mA)?
39. 39.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 watt
40. 40.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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