Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 902 · 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.What does a thermistor do? (a) senses how hot it is (b) beeps for an alarm (c) boosts a small signal (d) lets current go one way
2. 2.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
3. 3.🔺 A current of 0.5 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.True or false: the voltmeter measures voltage. (a) False (b) True
5. 5.🧮 A 9 V battery is joined to 5 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
6. 6.True or false: the ammeter measures current. (a) False (b) True
7. 7.🔺 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
8. 8.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
9. 9.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3600 Ω resistor? (a) orange-blue-orange (b) blue-orange-red (c) orange-blue-brown (d) orange-blue-red
11. 11.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the pipe colour (d) the flow of water
12. 12.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
13. 13.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
15. 15.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
16. 16.🌈 In the resistor colour code, which number does grey stand for?
17. 17.🧮 A 50 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)?
18. 18.True or false: to close the fridge quickly saves electricity. (a) False (b) True
19. 19.True or false: a diode senses how hot it is. (a) False (b) True
20. 20.🔺 A 3 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
21. 21.🔺 A current of 2.5 A flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to store charge (d) to make it brighter
23. 23.🌈 A resistor has the colour bands blue, yellow, red. What is its value (in ohms)?
24. 24.🌈 A resistor has the colour bands blue, black, orange. What is its value in kilo-ohms (kΩ)? =
25. 25.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
26. 26.🔺 A current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🔺 A current of 50 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
30. 30.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
31. 31.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
32. 32.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
34. 34.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
35. 35.📏 How many watts (W) is 4.4 kW?
36. 36.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
37. 37.Which of these is measured in amperes (A)? (a) how much a part resists (b) current (c) voltage (d) energy used each second
38. 38.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
39. 39.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
40. 40.📏 Which unit measures energy used each second? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)

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