Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 856 · 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.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
2. 2.🌈 In the resistor colour code, which number does blue stand for?
3. 3.⚡ A 36 W device works on 24 V. What current does it take (in amperes)? =
4. 4.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.True or false: the voltmeter is joined across a part. (a) True (b) False
7. 7.Which of these saves electricity? (a) switch off empty rooms (b) iron one shirt at a time (c) use old filament bulbs (d) run fans in empty rooms
8. 8.🧾 A 1000 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
9. 9.⚡ A 3 W device works on 1.5 V. What current does it take (in amperes)? =
10. 10.🌈 A resistor has the colour bands red, white, orange. What is its value (in ohms)?
11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 87000 Ω resistor? (a) grey-violet-red (b) grey-violet-orange (c) violet-grey-orange (d) grey-violet-yellow
12. 12.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
13. 13.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
14. 14.What does a thermistor do? (a) stores a little charge (b) blows if current is high (c) senses how hot it is (d) has coloured bands
15. 15.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 volt
17. 17.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
18. 18.True or false: the push of a cell is measured in amperes (A). (a) True (b) False
19. 19.🌈 A resistor has the colour bands orange, white, red. What is its value (in ohms)?
20. 20.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
21. 21.🔺 A 0.6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
22. 22.Which of these saves electricity? (a) set the AC to 24 °C (b) leave fridge door open (c) use old filament bulbs (d) leave the TV on standby
23. 23.🌈 A resistor has the colour bands red, brown, red. What is its value in kilo-ohms (kΩ)? =
24. 24.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🌈 A resistor has the colour bands brown, white, orange. What is its value (in ohms)?
26. 26.Which of these saves electricity? (a) use old filament bulbs (b) leave fridge door open (c) use LED lamps (d) run fans in empty rooms
27. 27.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
28. 28.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 36 Ω resistor? (a) blue-orange-black (b) yellow-blue-black (c) orange-blue-brown (d) orange-blue-black
30. 30.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
31. 31.What does a fuse do? (a) makes a beeping sound (b) senses how bright it is (c) limits the current (d) blows if current is high
32. 32.📏 Which unit measures voltage? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
33. 33.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
35. 35.True or false: a motor is a resistance knob. (a) True (b) False
36. 36.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) make light (d) measure heat
37. 37.🌈 In the resistor colour code, which number does green stand for?
38. 38.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
39. 39.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) low energy device (d) light-emitting diode
40. 40.📏 How many kilo-ohms (kΩ) is 8500 Ω? =

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