Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 373 · 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 current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
2. 2.Which of these saves electricity? (a) use old filament bulbs (b) leave the TV on standby (c) use LED lamps (d) iron one shirt at a time
3. 3.🌈 A resistor has the colour bands red, yellow, black. What is its value (in ohms)?
4. 4.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
5. 5.Which of these is measured in amperes (A)? (a) voltage (b) the push of a cell (c) energy used each second (d) the flow of charge
6. 6.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
7. 7.Which of these saves electricity? (a) run fans in empty rooms (b) iron one shirt at a time (c) leave fridge door open (d) unplug idle chargers
8. 8.🧩 Which component makes a beeping sound? (a) buzzer (b) motor (c) fuse (d) diode
9. 9.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
10. 10.True or false: the ammeter is joined across a part. (a) False (b) True
11. 11.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.📏 How many ohms (Ω) is 6.2 kΩ?
13. 13.🌈 A resistor has the colour bands violet, blue, brown. What is its value (in ohms)?
14. 14.True or false: to use LED lamps wastes electricity. (a) False (b) True
15. 15.Which of these wastes electricity? (a) switch off empty rooms (b) run fans in empty rooms (c) unplug idle chargers (d) use LED lamps
16. 16.🌈 In the resistor colour code, which number does violet stand for?
17. 17.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
18. 18.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a buzzer (d) a diode
19. 19.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to make it brighter (d) to store charge
20. 20.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.📏 How many amperes (A) is 510 mA? =
22. 22.📏 How many amperes (A) is 1160 mA? =
23. 23.🌈 A resistor has the colour bands green, orange, red. What is its value in kilo-ohms (kΩ)? =
24. 24.🔺 A 0.4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
25. 25.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
27. 27.🌈 A resistor has the colour bands orange, brown, orange. What is its value in kilo-ohms (kΩ)? =
28. 28.🧮 Resistors of 10 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
29. 29.📏 How many ohms (Ω) is 1.2 kΩ?
30. 30.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) their sum (d) less than either one
31. 31.⚡ 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
32. 32.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🧮 A 22 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
34. 34.Which of these is measured in amperes (A)? (a) voltage (b) current (c) the push of a cell (d) how much a part resists
35. 35.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
36. 36.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the pipe colour (c) the water pressure (d) the tap handle
39. 39.True or false: how much a part resists is measured in volts (V). (a) False (b) True
40. 40.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 5 % (d) 0 %

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