Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 388 · 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: to close the fridge quickly saves electricity. (a) True (b) False
2. 2.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I × R (c) V = R ÷ I (d) V = I ÷ R
3. 3.🔺 A current of 1.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.🔺 A current of 0.2 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.🧮 Resistors of 100 Ω, 22 Ω, 10 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
6. 6.💡 An LED is joined to a 5 V battery with no 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
7. 7.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) energy used each second (d) the size of a cell
8. 8.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 0 % (d) 50 %
12. 12.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
13. 13.⚡ A device works on 5 V and takes 1 A. What is its power (in watts)? =
14. 14.🌈 A resistor has the colour bands red, black, red. What is its value in kilo-ohms (kΩ)? =
15. 15.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = V × I (d) P = I ÷ V
16. 16.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
17. 17.True or false: the ammeter is joined in series. (a) True (b) False
18. 18.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
19. 19.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
20. 20.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets smaller (d) gets bigger
21. 21.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
22. 22.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.Which of these wastes electricity? (a) use old filament bulbs (b) use LED lamps (c) unplug idle chargers (d) set the AC to 24 °C
24. 24.True or false: the voltmeter is joined in series. (a) False (b) True
25. 25.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
26. 26.🔺 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
27. 27.🧮 A 1.2 V battery is joined to 4 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
28. 28.🌈 A resistor has the colour bands red, green, yellow. What is its value in kilo-ohms (kΩ)? =
29. 29.💡 An LED is joined to a 5 V battery through a 330 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
30. 30.True or false: to iron one shirt at a time saves electricity. (a) False (b) True
31. 31.🔺 A current of 0.1 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
33. 33.What does a motor do? (a) smooths a wobbly supply (b) beeps for an alarm (c) limits the current (d) makes things spin
34. 34.🧮 A 1.7 V battery is joined to 12 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
35. 35.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it makes a sound (d) it does not light
36. 36.True or false: energy used each second is measured in watts (W). (a) True (b) False
37. 37.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
38. 38.🔺 A current of 0.5 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.💡 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
40. 40.🧮 A 10 V battery is joined to 4 Ω and 6 Ω resistors in series. What current flows (in amperes)? =

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