Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 255 · 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.What does a buzzer do? (a) glows using little power (b) has coloured bands (c) beeps for an alarm (d) lets current go one way
2. 2.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
3. 3.🌈 A resistor has the colour bands grey, red, orange. What is its value (in ohms)?
4. 4.What does a potentiometer do? (a) is a resistance knob (b) stores a little charge (c) senses how bright it is (d) glows using little power
5. 5.Which of these is measured in watts (W)? (a) current (b) power (c) how much a part resists (d) resistance
6. 6.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to make it brighter (c) to change its colour (d) to store charge
7. 7.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🔺 A 20 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
9. 9.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) measure heat (d) spin a wheel
10. 10.📏 How many kilo-ohms (kΩ) is 3900 Ω? =
11. 11.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 50 % (d) 5 %
13. 13.What does a transistor do? (a) glows using little power (b) smooths a wobbly supply (c) boosts a small signal (d) makes a beeping sound
14. 14.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = R ÷ V (d) I = V ÷ R
15. 15.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
16. 16.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
17. 17.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light energy dial (d) light-emitting diode
18. 18.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
20. 20.True or false: a potentiometer turns a fan or wheels. (a) False (b) True
21. 21.⚡ A device works on 1.5 V and takes 0.5 A. What is its power (in watts)? =
22. 22.🔺 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
23. 23.True or false: a diode glows using little power. (a) True (b) False
24. 24.Which of these is measured in watts (W)? (a) current (b) energy used each second (c) the push of a cell (d) resistance
25. 25.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
26. 26.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) stays the same (d) becomes zero
27. 27.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
28. 28.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) smaller (d) zero
30. 30.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
31. 31.What does an LDR do? (a) senses how hot it is (b) senses how bright it is (c) makes a beeping sound (d) has coloured bands
32. 32.📏 Which unit measures the flow of charge? (a) volt (V) (b) ohm (Ω) (c) watt (W) (d) ampere (A)
33. 33.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🔍 Which is the odd one out? (a) leave fridge door open (b) use old filament bulbs (c) set the AC to 24 °C (d) run fans in empty rooms
35. 35.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
36. 36.True or false: a capacitor stores a little charge. (a) False (b) True
37. 37.Which of these is measured in volts (V)? (a) resistance (b) the flow of charge (c) how much a part resists (d) voltage
38. 38.🔺 An 8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
39. 39.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 16 Ω resistor? (a) brown-blue-black (b) red-blue-black (c) brown-blue-brown (d) blue-brown-black

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