Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 354 · 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 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🌈 In the resistor colour code, which number does grey stand for?
3. 3.🌈 A resistor has the colour bands yellow, white, black. What is its value (in ohms)?
4. 4.What does a thermistor do? (a) senses how hot it is (b) boosts a small signal (c) is a resistance knob (d) blows if current is high
5. 5.🧮 A 12 V battery is joined to 12 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
6. 6.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
7. 7.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
8. 8.🧩 Which component blows if current is high? (a) thermistor (b) potentiometer (c) transistor (d) fuse
9. 9.⚡ A 9 W device works on 9 V. What current does it take (in amperes)? =
10. 10.🧩 Which component smooths a wobbly supply? (a) transistor (b) fuse (c) capacitor (d) resistor
11. 11.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) smaller (d) zero
12. 12.🧾 A 50 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
13. 13.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = R ÷ I (c) V = I × R (d) V = I ÷ R
14. 14.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
15. 15.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
16. 16.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
17. 17.True or false: the voltmeter measures voltage. (a) True (b) False
18. 18.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
19. 19.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = I ÷ V (d) P = V ÷ I
20. 20.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
21. 21.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the size of a cell (d) the length of a wire
22. 22.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
25. 25.🧮 A 47 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)?
26. 26.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
27. 27.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
28. 28.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
29. 29.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
30. 30.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =
31. 31.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
32. 32.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
33. 33.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
34. 34.Which of these is measured in amperes (A)? (a) the push of a cell (b) energy used each second (c) power (d) current
35. 35.True or false: the voltmeter is joined across a part. (a) False (b) True
36. 36.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 37 Ω resistor? (a) violet-orange-black (b) orange-violet-black (c) orange-violet-brown (d) yellow-violet-black
38. 38.📏 Which unit measures voltage? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
39. 39.🌈 A resistor has the colour bands red, white, black. What is its value (in ohms)?
40. 40.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?

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