Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 877 · 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.True or false: a diode blows if current is high. (a) False (b) True
2. 2.True or false: to iron one shirt at a time wastes electricity. (a) False (b) True
3. 3.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
4. 4.True or false: to leave the TV on standby wastes electricity. (a) False (b) True
5. 5.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
6. 6.🔺 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
7. 7.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🌈 In the resistor colour code, which number does yellow stand for?
9. 9.📏 How many ohms (Ω) is 0.5 kΩ?
10. 10.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
11. 11.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
12. 12.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the pipe colour (c) the water pressure (d) the flow of water
13. 13.True or false: to set the AC to 24 °C saves electricity. (a) True (b) False
14. 14.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
15. 15.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 300 Ω resistor? (a) yellow-orange-brown (b) orange-black-brown (c) orange-black-red (d) orange-black-black
16. 16.True or false: a motor makes a beeping sound. (a) True (b) False
17. 17.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.True or false: a buzzer makes a beeping sound. (a) False (b) True
19. 19.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
20. 20.🧮 Resistors of 10 Ω, 47 Ω, 20 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
21. 21.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) zero (d) smaller
22. 22.🌈 A resistor has the colour bands violet, blue, brown. What is its value (in ohms)?
23. 23.True or false: the voltmeter measures voltage. (a) False (b) True
24. 24.🌈 A resistor has the colour bands red, brown, red. What is its value in kilo-ohms (kΩ)? =
25. 25.What does a resistor do? (a) smooths a wobbly supply (b) limits the current (c) is a resistance knob (d) senses how hot it is
26. 26.True or false: to close the fridge quickly wastes electricity. (a) True (b) False
27. 27.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
28. 28.💡 An LED is joined to a 9 V battery through a 330 Ω 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
29. 29.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
30. 30.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🌈 A resistor has the colour bands grey, black, yellow. What is its value in kilo-ohms (kΩ)? =
32. 32.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave the TV on standby (c) leave fridge door open (d) use daylight to read
33. 33.💡 An LED is joined to a 6 V battery through a 330 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) may burn out (c) does not light
34. 34.🌈 In the resistor colour code, which number does blue stand for?
35. 35.🧮 A 6 V battery is joined to 6 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
36. 36.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.⚡ A device works on 12 V and takes 0.25 A. What is its power (in watts)? =
38. 38.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) an LED lamp (d) a filament bulb
39. 39.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
40. 40.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?

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