Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 390 · 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.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
2. 2.🔺 A current of 2.5 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
3. 3.What does a resistor do? (a) has coloured bands (b) senses how bright it is (c) beeps for an alarm (d) makes a beeping sound
4. 4.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
5. 5.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
6. 6.🔺 A 36 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
7. 7.🔺 A current of 50 mA flows when 11 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.⚡ A 3 W device works on 1.5 V. What current does it take (in amperes)? =
9. 9.🌈 In the resistor colour code, which number does green stand for?
10. 10.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
11. 11.🧩 Which component makes a beeping sound? (a) LDR (b) buzzer (c) resistor (d) diode
12. 12.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
13. 13.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the gold band (d) the one nearest an end
14. 14.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
15. 15.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = I × R (d) V = R ÷ I
16. 16.🧮 A 150 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
17. 17.📏 Which unit measures current? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
18. 18.🧩 Which component lets current go one way? (a) fuse (b) transistor (c) motor (d) diode
19. 19.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
20. 20.🔍 Which is the odd one out? (a) use LED lamps (b) iron one shirt at a time (c) use daylight to read (d) switch off empty rooms
21. 21.🔺 A 2 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
22. 22.🧾 A 250 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
23. 23.⚡ A 12 W device works on 6 V. What current does it take (in amperes)? =
24. 24.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it changes colour (d) it does not light
25. 25.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 90 Ω resistor? (a) brown-black-black (b) brown-white-black (c) white-black-brown (d) white-black-black
27. 27.🔺 A current of 25 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.🔺 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
29. 29.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
30. 30.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) the water pressure (c) a bigger tank (d) the flow of water
31. 31.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1000 (c) 1024 (d) 10
32. 32.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
35. 35.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🌈 In the resistor colour code, which number does white stand for?
37. 37.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.What does a capacitor do? (a) beeps for an alarm (b) stores a little charge (c) has coloured bands (d) is a resistance knob
39. 39.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.📏 How many watts (W) is 0.6 kW?

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