Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 482 · 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.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
2. 2.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
3. 3.Which of these wastes electricity? (a) set the AC to 24 °C (b) leave fridge door open (c) unplug idle chargers (d) use daylight to read
4. 4.True or false: a fuse blows if current is high. (a) False (b) True
5. 5.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
6. 6.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
7. 7.🧩 Which component limits the current? (a) buzzer (b) transistor (c) LED (d) resistor
8. 8.Which of these saves electricity? (a) run fans in empty rooms (b) leave fridge door open (c) set the AC to 24 °C (d) use old filament bulbs
9. 9.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7100 Ω resistor? (a) violet-brown-brown (b) brown-violet-red (c) violet-brown-orange (d) violet-brown-red
10. 10.📏 Which unit measures the push of a cell? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
11. 11.📏 How many kilo-ohms (kΩ) is 6100 Ω? =
12. 12.Which of these is measured in amperes (A)? (a) how much a part resists (b) the push of a cell (c) current (d) energy used each second
13. 13.⚡ A 24 W device works on 12 V. What current does it take (in amperes)? =
14. 14.🌈 A resistor has the colour bands blue, orange, brown. What is its value (in ohms)?
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.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🧮 A 33 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.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
19. 19.🔺 A current of 1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A 2 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
21. 21.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
22. 22.🔺 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
23. 23.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
24. 24.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
25. 25.🧾 A 1500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
26. 26.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1000 (d) 1024
28. 28.💡 An LED is joined to a 9 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
29. 29.🧩 Which component lets current go one way? (a) capacitor (b) LDR (c) buzzer (d) diode
30. 30.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
31. 31.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
32. 32.True or false: a fuse has coloured bands. (a) False (b) True
33. 33.🌈 A resistor has the colour bands orange, brown, yellow. What is its value in kilo-ohms (kΩ)? =
34. 34.🔺 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
35. 35.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 73 Ω resistor? (a) violet-orange-black (b) grey-orange-black (c) violet-orange-brown (d) orange-violet-black
37. 37.🔺 A 37.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
38. 38.🌈 A resistor has the colour bands red, red, orange. What is its value (in ohms)?
39. 39.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
40. 40.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) light-emitting diode (d) low energy device

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