Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 160 · 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 resistor has the colour bands red, green, yellow. What is its value in kilo-ohms (kΩ)? =
2. 2.True or false: to close the fridge quickly saves electricity. (a) False (b) True
3. 3.📏 How many kilowatts (kW) is 900 W? =
4. 4.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
5. 5.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.True or false: a buzzer beeps for an alarm. (a) False (b) True
7. 7.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8300 Ω resistor? (a) grey-orange-red (b) grey-orange-brown (c) grey-orange-orange (d) orange-grey-red
8. 8.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
9. 9.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
10. 10.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) large electric dial (d) low energy device
11. 11.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
12. 12.🔺 A 12 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
13. 13.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
14. 14.🧮 A 2 V battery is joined to 5 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
15. 15.⚡ A device works on 5 V and takes 2 A. What is its power (in watts)? =
16. 16.🧩 Which component is a resistance knob? (a) diode (b) resistor (c) potentiometer (d) LED
17. 17.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
18. 18.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
19. 19.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
20. 20.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
21. 21.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to store charge (d) to make it brighter
22. 22.True or false: a diode is a resistance knob. (a) True (b) False
23. 23.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
24. 24.Which of these is measured in amperes (A)? (a) resistance (b) the flow of charge (c) voltage (d) how much a part resists
25. 25.📏 How many ohms (Ω) is 4.8 kΩ?
26. 26.📏 How many kilowatts (kW) is 3450 W? =
27. 27.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V ÷ R (c) I = V × R (d) I = V + R
28. 28.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
29. 29.🧮 Resistors of 330 Ω, 33 Ω, 47 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
30. 30.📏 How many watts (W) is 4.1 kW?
31. 31.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
32. 32.Which of these wastes electricity? (a) use LED lamps (b) unplug idle chargers (c) set the AC to 24 °C (d) leave fridge door open
33. 33.🧾 A 50 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
34. 34.What does a motor do? (a) smooths a wobbly supply (b) glows using little power (c) has coloured bands (d) makes things spin
35. 35.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🧩 Which component turns a fan or wheels? (a) motor (b) transistor (c) buzzer (d) LED
38. 38.Which of these wastes electricity? (a) use daylight to read (b) use LED lamps (c) iron one shirt at a time (d) unplug idle chargers
39. 39.🧩 Which component stores a little charge? (a) capacitor (b) LDR (c) motor (d) resistor
40. 40.🔺 A current of 1.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?

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