Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 53 · 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 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
3. 3.What does a capacitor do? (a) blows if current is high (b) limits the current (c) senses how bright it is (d) stores a little charge
4. 4.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
5. 5.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a motor (c) an LED (d) a resistor
8. 8.🧩 Which component stores a little charge? (a) diode (b) potentiometer (c) capacitor (d) resistor
9. 9.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
10. 10.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
11. 11.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the one nearest an end (d) the gold band
12. 12.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
13. 13.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
14. 14.Which of these saves electricity? (a) use LED lamps (b) iron one shirt at a time (c) use old filament bulbs (d) run fans in empty rooms
15. 15.🌈 A resistor has the colour bands yellow, green, red. What is its value in kilo-ohms (kΩ)? =
16. 16.🌈 In the resistor colour code, which number does red stand for?
17. 17.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
18. 18.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
19. 19.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
20. 20.🧩 A capacitor in a circuit can … (a) store charge briefly (b) measure heat (c) make light (d) spin a wheel
21. 21.📏 How many kilowatts (kW) is 1000 W? =
22. 22.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
23. 23.🧮 A 33 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
24. 24.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) always zero (d) less than either one
25. 25.True or false: voltage is measured in volts (V). (a) False (b) True
26. 26.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.⚡ A 0.375 W device works on 1.5 V. What current does it take (in amperes)? =
28. 28.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 50000 Ω resistor? (a) green-black-yellow (b) green-black-red (c) green-black-orange (d) blue-green-orange
30. 30.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
31. 31.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
32. 32.🧮 A 9 V battery is joined to 5 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
33. 33.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
35. 35.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
36. 36.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
37. 37.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.True or false: a capacitor glows using little power. (a) True (b) False
39. 39.🔍 Which is the odd one out? (a) leave fridge door open (b) iron one shirt at a time (c) leave the TV on standby (d) set the AC to 24 °C
40. 40.📏 How many ohms (Ω) is 6.5 kΩ?

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