Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 349 · 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.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
2. 2.🔺 A 0.8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
3. 3.Which of these is measured in ohms (Ω)? (a) resistance (b) energy used each second (c) power (d) the push of a cell
4. 4.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
5. 5.🌈 A resistor has the colour bands green, grey, yellow. What is its value in kilo-ohms (kΩ)? =
6. 6.📏 How many amperes (A) is 2360 mA? =
7. 7.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
8. 8.🌈 A resistor has the colour bands green, green, red. What is its value in kilo-ohms (kΩ)? =
9. 9.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
10. 10.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
11. 11.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
12. 12.🧩 Which component stores a little charge? (a) motor (b) resistor (c) LDR (d) capacitor
13. 13.True or false: a thermistor senses how hot it is. (a) False (b) True
14. 14.True or false: the ammeter is joined across a part. (a) False (b) True
15. 15.🌈 In the resistor colour code, which number does red stand for?
16. 16.📏 Which unit measures current? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
17. 17.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
18. 18.🌈 In the resistor colour code, which number does orange stand for?
19. 19.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) smaller (d) zero
20. 20.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 52000 Ω resistor? (a) green-red-yellow (b) green-red-orange (c) green-red-red (d) red-green-orange
22. 22.Which of these wastes electricity? (a) unplug idle chargers (b) set the AC to 24 °C (c) leave fridge door open (d) use LED lamps
23. 23.🧮 A 150 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
24. 24.What does a transistor do? (a) makes a beeping sound (b) turns a fan or wheels (c) senses how hot it is (d) boosts a small signal
25. 25.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
26. 26.🧩 Which component makes things spin? (a) resistor (b) thermistor (c) potentiometer (d) motor
27. 27.🧮 A 68 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
28. 28.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
29. 29.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
30. 30.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
31. 31.🧩 Which component beeps for an alarm? (a) diode (b) buzzer (c) resistor (d) fuse
32. 32.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to store charge (d) to make it brighter
33. 33.What does a diode do? (a) lets current go one way (b) senses how bright it is (c) makes things spin (d) blows if current is high
34. 34.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I + R (d) V = I ÷ R
35. 35.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🧮 A 4.4 V battery is joined to 10 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
37. 37.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
38. 38.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light energy dial (d) light-emitting diode
39. 39.🧮 Resistors of 33 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
40. 40.🌈 Which band is read first on a resistor? (a) the gold band (b) any band (c) the widest gap (d) the one nearest an end

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