Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 545 · 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: current is measured in amperes (A). (a) False (b) True
2. 2.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end
3. 3.🧩 Which component is a resistance knob? (a) diode (b) potentiometer (c) capacitor (d) buzzer
4. 4.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
5. 5.🔺 A current of 1 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.🧮 A 2.4 V battery is joined to 8 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
7. 7.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a motor (d) a fuse
8. 8.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V ÷ I (d) R = V × I
9. 9.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
10. 10.What does a buzzer do? (a) glows using little power (b) lets current go one way (c) smooths a wobbly supply (d) beeps for an alarm
11. 11.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
12. 12.🔺 A current of 2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
13. 13.Which of these wastes electricity? (a) leave the TV on standby (b) switch off empty rooms (c) use LED lamps (d) set the AC to 24 °C
14. 14.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
15. 15.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
16. 16.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 ampere
17. 17.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.🧩 Which component stores a little charge? (a) capacitor (b) thermistor (c) potentiometer (d) buzzer
19. 19.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
20. 20.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) an oil lamp (c) a candle (d) a filament bulb
21. 21.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
22. 22.🔺 A current of 50 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🌈 In the resistor colour code, which number does grey stand for?
26. 26.True or false: the ammeter measures voltage. (a) True (b) False
27. 27.🌈 A resistor has the colour bands violet, black, yellow. What is its value in kilo-ohms (kΩ)? =
28. 28.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
29. 29.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
30. 30.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
31. 31.Which of these wastes electricity? (a) unplug idle chargers (b) switch off empty rooms (c) close the fridge quickly (d) iron one shirt at a time
32. 32.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
33. 33.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
34. 34.📏 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
35. 35.True or false: the ammeter measures current. (a) False (b) True
36. 36.🔺 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
37. 37.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
38. 38.📏 Which unit measures the push of a cell? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
39. 39.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
40. 40.🧮 Resistors of 10 Ω, 150 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?

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