Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 981 · 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 1.2 W device works on 12 V. What current does it take (in amperes)? =
2. 2.True or false: a buzzer beeps for an alarm. (a) False (b) True
3. 3.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 volt (d) 1 kilowatt-hour (kWh)
4. 4.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 14000 Ω resistor? (a) brown-yellow-orange (b) brown-yellow-red (c) yellow-brown-orange (d) brown-yellow-yellow
5. 5.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
6. 6.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
7. 7.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
8. 8.What does a buzzer do? (a) beeps for an alarm (b) turns a fan or wheels (c) has coloured bands (d) is a resistance knob
9. 9.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = V ÷ I (d) P = I ÷ V
10. 10.What does a thermistor do? (a) lets current go one way (b) senses how hot it is (c) limits the current (d) makes a beeping sound
11. 11.🔺 A current of 1 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) low energy device (d) light energy dial
13. 13.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) more than either one (d) always zero
14. 14.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
15. 15.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = R ÷ V (d) I = V ÷ R
16. 16.📏 How many kilo-ohms (kΩ) is 800 Ω? =
17. 17.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
18. 18.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
19. 19.What does a motor do? (a) makes a beeping sound (b) senses how bright it is (c) boosts a small signal (d) makes things spin
20. 20.Which of these saves electricity? (a) leave fridge door open (b) use old filament bulbs (c) leave the TV on standby (d) switch off empty rooms
21. 21.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
22. 22.🌈 A resistor has the colour bands brown, orange, red. What is its value in kilo-ohms (kΩ)? =
23. 23.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
24. 24.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 37000 Ω resistor? (a) orange-violet-orange (b) orange-violet-red (c) violet-orange-orange (d) orange-violet-yellow
25. 25.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
26. 26.True or false: a buzzer makes a beeping sound. (a) True (b) False
27. 27.📏 How many milliamperes (mA) is 0.63 A?
28. 28.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) measure heat (d) make light
29. 29.📏 How many kilo-ohms (kΩ) is 9500 Ω? =
30. 30.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
31. 31.🌈 In the resistor colour code, which number does blue stand for?
32. 32.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) unplug idle chargers (c) use daylight to read (d) use old filament bulbs
34. 34.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
35. 35.True or false: the voltmeter is joined across a part. (a) True (b) False
36. 36.🧩 Which component beeps for an alarm? (a) diode (b) buzzer (c) potentiometer (d) thermistor
37. 37.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🌈 A resistor has the colour bands violet, violet, orange. What is its value (in ohms)?
39. 39.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
40. 40.🔺 A current of 0.1 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?

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