Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 817 · 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.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I ÷ R (d) V = I + R
2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3000 Ω resistor? (a) orange-black-orange (b) yellow-orange-red (c) orange-black-brown (d) orange-black-red
3. 3.🔺 A 6 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
4. 4.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
5. 5.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
6. 6.🔺 A current of 2 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.True or false: how much a part resists is measured in watts (W). (a) True (b) False
8. 8.🌈 A resistor has the colour bands orange, grey, red. What is its value (in ohms)?
9. 9.🧩 Which component senses how hot it is? (a) potentiometer (b) resistor (c) thermistor (d) buzzer
10. 10.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
11. 11.What does a resistor do? (a) boosts a small signal (b) has coloured bands (c) lets current go one way (d) beeps for an alarm
12. 12.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) a filament bulb (d) an oil lamp
13. 13.🔺 A current of 0.5 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
14. 14.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
15. 15.🔺 A 30 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
16. 16.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) a narrow pipe (c) the water pressure (d) the pipe colour
17. 17.Which of these saves electricity? (a) run fans in empty rooms (b) leave fridge door open (c) leave the TV on standby (d) use LED lamps
18. 18.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
19. 19.True or false: the ammeter measures voltage. (a) True (b) False
20. 20.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
21. 21.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🔍 Which is the odd one out? (a) leave fridge door open (b) set the AC to 24 °C (c) leave the TV on standby (d) use old filament bulbs
23. 23.📏 How many kilo-ohms (kΩ) is 4600 Ω? =
24. 24.💡 An LED is joined to a 5 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
25. 25.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
26. 26.True or false: to run fans in empty rooms wastes electricity. (a) False (b) True
27. 27.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
28. 28.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
29. 29.🧮 Resistors of 68 Ω, 33 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
30. 30.True or false: an LED glows using little power. (a) True (b) False
31. 31.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
32. 32.🌈 A resistor has the colour bands red, brown, orange. What is its value (in ohms)?
33. 33.🔍 Which is the odd one out? (a) use LED lamps (b) leave fridge door open (c) switch off empty rooms (d) unplug idle chargers
34. 34.Which of these is measured in watts (W)? (a) how much a part resists (b) power (c) the flow of charge (d) voltage
35. 35.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
36. 36.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
37. 37.True or false: the voltmeter measures current. (a) True (b) False
38. 38.Which of these is measured in amperes (A)? (a) how much a part resists (b) energy used each second (c) voltage (d) the flow of charge
39. 39.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
40. 40.What does a fuse do? (a) smooths a wobbly supply (b) has coloured bands (c) blows if current is high (d) boosts a small signal

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