Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 327 · 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 run fans in empty rooms? (a) saves electricity (b) wastes electricity
2. 2.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
3. 3.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) may burn out (c) does not light
4. 4.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) smaller (d) bigger
6. 6.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
7. 7.True or false: a capacitor stores a little charge. (a) False (b) True
8. 8.🌈 A resistor has the colour bands brown, red, orange. What is its value in kilo-ohms (kΩ)? =
9. 9.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
12. 12.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
13. 13.⚡ A device works on 6 V and takes 0.25 A. What is its power (in watts)? =
14. 14.What does a buzzer do? (a) is a resistance knob (b) stores a little charge (c) smooths a wobbly supply (d) makes a beeping sound
15. 15.Which of these saves electricity? (a) iron one shirt at a time (b) set the AC to 24 °C (c) leave fridge door open (d) run fans in empty rooms
16. 16.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 60 (c) 1000 (d) 100
17. 17.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
18. 18.📏 Which unit measures power? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
19. 19.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 590 Ω resistor? (a) white-green-brown (b) green-white-black (c) green-white-brown (d) green-white-red
21. 21.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
22. 22.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
24. 24.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) an oil lamp (c) a filament bulb (d) a candle
25. 25.🧾 A 200 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
26. 26.🧩 Which component glows using little power? (a) LED (b) resistor (c) fuse (d) capacitor
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9000 Ω resistor? (a) white-black-orange (b) brown-white-red (c) white-black-red (d) white-black-brown
28. 28.🧩 Which component is a resistance knob? (a) motor (b) LED (c) resistor (d) potentiometer
29. 29.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
30. 30.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
31. 31.Which of these is measured in amperes (A)? (a) current (b) the push of a cell (c) voltage (d) power
32. 32.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) the gold band (d) any band
33. 33.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 26 Ω resistor? (a) orange-blue-black (b) blue-red-black (c) red-blue-black (d) red-blue-brown
35. 35.🧮 A 0.7 V battery is joined to 4 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
36. 36.📏 How many ohms (Ω) is 5.3 kΩ?
37. 37.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
38. 38.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
39. 39.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 ampere
40. 40.🌈 In the resistor colour code, which number does black stand for?

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