Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 204 · 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 unit measures current? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
2. 2.🧮 A 2.2 V battery is joined to 6 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
3. 3.🧩 Which component glows using little power? (a) buzzer (b) LED (c) capacitor (d) motor
4. 4.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
5. 5.True or false: a diode has coloured bands. (a) False (b) True
6. 6.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
7. 7.🌈 A resistor has the colour bands brown, white, brown. What is its value (in ohms)?
8. 8.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
9. 9.Which of these is measured in ohms (Ω)? (a) resistance (b) the flow of charge (c) energy used each second (d) voltage
10. 10.🔺 A 4.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
11. 11.💡 An LED is joined to a 9 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
12. 12.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
13. 13.🔺 A current of 3 A flows when 36 V is joined across a resistor. What is its resistance (in ohms)?
14. 14.True or false: to use LED lamps saves electricity. (a) False (b) True
15. 15.🧩 Which component makes a beeping sound? (a) fuse (b) diode (c) buzzer (d) motor
16. 16.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🧮 A 50 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
18. 18.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = V × I (d) R = I ÷ V
19. 19.🧮 A 150 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
20. 20.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?
21. 21.🌈 In the resistor colour code, which number does blue stand for?
22. 22.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
23. 23.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.🧮 Resistors of 100 Ω, 150 Ω, 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
25. 25.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an LED lamp (d) an oil lamp
26. 26.🔺 A 6.6 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
27. 27.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to limit the current (d) to make it brighter
28. 28.🔺 A current of 0.25 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.📏 Which unit measures voltage? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
30. 30.📏 Which unit measures how much a part resists? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
31. 31.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water pressure (c) the tap handle (d) the water tank lid
32. 32.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
33. 33.📏 How many milliamperes (mA) is 1.8 A?
34. 34.🌈 In the resistor colour code, which number does white stand for?
35. 35.What does an LDR do? (a) limits the current (b) senses how hot it is (c) has coloured bands (d) senses how bright it is
36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 27 Ω resistor? (a) red-violet-brown (b) orange-violet-black (c) red-violet-black (d) violet-red-black
37. 37.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
38. 38.True or false: a capacitor stores a little charge. (a) False (b) True
39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
40. 40.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it lights brighter (d) it does not light

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