Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 487 · 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.🧮 A 22 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
2. 2.🔍 Which is the odd one out? (a) close the fridge quickly (b) switch off empty rooms (c) unplug idle chargers (d) leave fridge door open
3. 3.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
4. 4.💡 A red LED uses 2 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
5. 5.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 91 Ω resistor? (a) white-brown-brown (b) brown-brown-black (c) brown-white-black (d) white-brown-black
7. 7.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
8. 8.True or false: a buzzer makes a beeping sound. (a) False (b) True
9. 9.🌈 A resistor has the colour bands orange, green, black. What is its value (in ohms)?
10. 10.Which of these saves electricity? (a) use LED lamps (b) iron one shirt at a time (c) leave fridge door open (d) leave the TV on standby
11. 11.💡 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
12. 12.🔺 A current of 0.5 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
14. 14.🔺 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
15. 15.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
16. 16.🌈 A resistor has the colour bands blue, white, red. What is its value in kilo-ohms (kΩ)? =
17. 17.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
18. 18.🔺 A current of 3 A flows when 45 V is joined across a resistor. What is its resistance (in ohms)?
19. 19.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🧩 Which component glows using little power? (a) LED (b) resistor (c) LDR (d) capacitor
21. 21.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
22. 22.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 11000 Ω resistor? (a) brown-brown-orange (b) brown-brown-yellow (c) brown-brown-red (d) brown-red-orange
24. 24.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🌈 A resistor has the colour bands orange, orange, black. What is its value (in ohms)?
27. 27.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a resistor (d) a motor
29. 29.🧮 Resistors of 22 Ω, 50 Ω, 150 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
30. 30.💡 An LED is joined to a 6 V battery through a 470 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
31. 31.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
32. 32.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) measure heat (d) make light
33. 33.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
34. 34.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 29000 Ω resistor? (a) red-white-yellow (b) red-white-orange (c) red-white-red (d) white-red-orange
36. 36.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
37. 37.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.True or false: voltage is measured in ohms (Ω). (a) False (b) True
39. 39.🧮 A 3.5 V battery is joined to 2 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
40. 40.🧮 Resistors of 22 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?

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