Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 572 · 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 device works on 6 V and takes 0.1 A. What is its power (in watts)? =
2. 2.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) store charge briefly (d) measure heat
3. 3.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) the widest gap (d) any band
5. 5.⚡ A 12 W device works on 24 V. What current does it take (in amperes)? =
6. 6.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
7. 7.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
8. 8.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
9. 9.💡 An LED is joined to a 6 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
10. 10.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
11. 11.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.🧮 A 0.7 V battery is joined to 4 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
13. 13.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
14. 14.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
15. 15.📏 How many kilowatts (kW) is 600 W? =
16. 16.🔍 Which is the odd one out? (a) iron one shirt at a time (b) use daylight to read (c) leave the TV on standby (d) use old filament bulbs
17. 17.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
18. 18.🧩 Which component senses how hot it is? (a) diode (b) potentiometer (c) thermistor (d) fuse
19. 19.True or false: the ammeter is joined in series. (a) True (b) False
20. 20.🧮 An 8 V battery is joined to 6 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
21. 21.🔺 A current of 40 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
23. 23.True or false: a motor turns a fan or wheels. (a) False (b) True
24. 24.⚡ A device works on 24 V and takes 0.1 A. What is its power (in watts)? =
25. 25.🌈 A resistor has the colour bands blue, red, brown. What is its value (in ohms)?
26. 26.🧾 A 500 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
27. 27.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a diode (d) a capacitor
28. 28.Which of these is measured in watts (W)? (a) power (b) the push of a cell (c) how much a part resists (d) resistance
29. 29.What does an LDR do? (a) senses how hot it is (b) limits the current (c) senses how bright it is (d) is a resistance knob
30. 30.🧮 A 330 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
31. 31.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
32. 32.🧩 Which component glows using little power? (a) LDR (b) resistor (c) motor (d) LED
33. 33.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
34. 34.🧩 Which component beeps for an alarm? (a) buzzer (b) diode (c) transistor (d) resistor
35. 35.True or false: the ammeter is joined across a part. (a) True (b) False
36. 36.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🔍 Which is the odd one out? (a) run fans in empty rooms (b) unplug idle chargers (c) switch off empty rooms (d) use LED lamps
39. 39.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.🧮 A 1.3 V battery is joined to 3 Ω and 10 Ω resistors in series. What current flows (in amperes)? =

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