Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 993 · 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 68 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
2. 2.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🧮 Resistors of 22 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
4. 4.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
5. 5.🔺 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
6. 6.🧮 A 100 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
7. 7.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
8. 8.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
9. 9.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
10. 10.⚡ A device works on 1.5 V and takes 2 A. What is its power (in watts)? =
11. 11.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
12. 12.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
13. 13.🧮 An 11 V battery is joined to 6 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
14. 14.🧮 A 470 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)?
15. 15.True or false: to leave fridge door open wastes electricity. (a) False (b) True
16. 16.🧾 A 50 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
17. 17.🔍 Which is the odd one out? (a) run fans in empty rooms (b) use old filament bulbs (c) unplug idle chargers (d) iron one shirt at a time
18. 18.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
19. 19.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
20. 20.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
21. 21.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
22. 22.🔍 Which is the odd one out? (a) switch off empty rooms (b) use old filament bulbs (c) unplug idle chargers (d) use daylight to read
23. 23.📏 How many ohms (Ω) is 5.3 kΩ?
24. 24.⚡ A device works on 1.5 V and takes 0.5 A. What is its power (in watts)? =
25. 25.📏 Which unit measures current? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
26. 26.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
27. 27.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
28. 28.📏 How many watts (W) is 4.3 kW?
29. 29.🌈 A resistor has the colour bands white, grey, brown. What is its value (in ohms)?
30. 30.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
31. 31.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 60 (c) 1000 (d) 100
32. 32.🧮 Resistors of 330 Ω, 20 Ω, 22 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
33. 33.⚡ A 9 W device works on 6 V. What current does it take (in amperes)? =
34. 34.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
35. 35.🌈 A resistor has the colour bands violet, grey, red. What is its value (in ohms)?
36. 36.True or false: voltage is measured in ohms (Ω). (a) True (b) False
37. 37.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) stays the same (d) becomes zero
39. 39.💡 An LED is joined to a 3 V battery through a 1000 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
40. 40.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to store charge (d) to change its colour

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