Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 838 · 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 is the odd one out? (a) switch off empty rooms (b) use daylight to read (c) set the AC to 24 °C (d) leave fridge door open
2. 2.🧮 Resistors of 100 Ω, 220 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
3. 3.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
4. 4.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
5. 5.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
6. 6.What does a buzzer do? (a) beeps for an alarm (b) boosts a small signal (c) senses how hot it is (d) senses how bright it is
7. 7.🌈 A resistor has the colour bands grey, green, black. What is its value (in ohms)?
8. 8.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the gold band (d) the widest gap
9. 9.🔺 A current of 40 mA flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.🧮 A 33 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)?
11. 11.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to store charge (d) to change its colour
12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
13. 13.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
14. 14.🔺 A 5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
15. 15.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) more than either one (d) their sum
16. 16.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
17. 17.🔺 A current of 2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 50 % (d) 5 %
19. 19.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A current of 3 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V + R (d) I = V ÷ R
22. 22.🔍 Which is the odd one out? (a) close the fridge quickly (b) use LED lamps (c) iron one shirt at a time (d) use daylight to read
23. 23.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
24. 24.True or false: a thermistor limits the current. (a) True (b) False
25. 25.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
26. 26.🔺 A 2 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
27. 27.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
28. 28.📏 How many milliamperes (mA) is 1.51 A?
29. 29.True or false: to close the fridge quickly wastes electricity. (a) True (b) False
30. 30.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
31. 31.What does a motor do? (a) stores a little charge (b) makes things spin (c) lets current go one way (d) is a resistance knob
32. 32.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8100 Ω resistor? (a) brown-grey-red (b) grey-brown-brown (c) grey-brown-red (d) grey-brown-orange
33. 33.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) store charge briefly (d) spin a wheel
36. 36.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
37. 37.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V + I (d) R = V × I
38. 38.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light-emitting diode (d) light energy dial
39. 39.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
40. 40.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?

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