Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 642 · 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.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
2. 2.True or false: the voltmeter is joined in series. (a) False (b) True
3. 3.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = R ÷ I (c) V = I ÷ R (d) V = I × R
4. 4.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
5. 5.📏 How many milliamperes (mA) is 0.74 A?
6. 6.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🧩 Which component turns a fan or wheels? (a) LED (b) LDR (c) resistor (d) motor
8. 8.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
9. 9.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
10. 10.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
11. 11.What does a fuse do? (a) senses how hot it is (b) makes things spin (c) limits the current (d) blows if current is high
12. 12.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.🧮 Resistors of 470 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
14. 14.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
15. 15.Which of these is measured in volts (V)? (a) how much a part resists (b) voltage (c) energy used each second (d) the flow of charge
16. 16.⚡ An 18 W device works on 12 V. What current does it take (in amperes)? =
17. 17.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9700 Ω resistor? (a) white-violet-red (b) violet-white-red (c) white-violet-brown (d) white-violet-orange
19. 19.🌈 In the resistor colour code, which number does yellow stand for?
20. 20.True or false: an LED glows using little power. (a) True (b) False
21. 21.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
22. 22.🧮 Resistors of 20 Ω, 330 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
23. 23.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🔺 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
27. 27.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.What does a motor do? (a) lets current go one way (b) has coloured bands (c) makes things spin (d) makes a beeping sound
29. 29.True or false: the voltmeter is joined across a part. (a) False (b) True
30. 30.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
31. 31.📏 How many ohms (Ω) is 4.1 kΩ?
32. 32.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it changes colour (d) it does not light
34. 34.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
35. 35.🔺 A 2 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
36. 36.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
37. 37.🌈 A resistor has the colour bands blue, blue, orange. What is its value (in ohms)?
38. 38.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
39. 39.Which of these saves electricity? (a) iron one shirt at a time (b) run fans in empty rooms (c) leave the TV on standby (d) use LED lamps
40. 40.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to change its colour (d) to make it brighter

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