Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 240 · 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.True or false: a buzzer makes a beeping sound. (a) True (b) False
2. 2.🧩 Which component makes things spin? (a) diode (b) motor (c) potentiometer (d) resistor
3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
4. 4.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
5. 5.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
6. 6.🧮 A 9 V battery is joined to 5 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
7. 7.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) stay the same (d) smaller
8. 8.🧮 A 12 V battery is joined to 2 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
9. 9.🌈 A resistor has the colour bands green, green, orange. What is its value (in ohms)?
10. 10.🧮 Resistors of 50 Ω, 10 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
12. 12.True or false: a motor smooths a wobbly supply. (a) False (b) True
13. 13.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 watt
14. 14.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap
15. 15.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
16. 16.🌈 In the resistor colour code, which number does brown stand for?
17. 17.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 50 % (d) 5 %
18. 18.📏 How many ohms (Ω) is 6.4 kΩ?
19. 19.🧮 A 1.3 V battery is joined to 5 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
20. 20.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
21. 21.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = V ÷ I (d) R = I ÷ V
22. 22.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A 20 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
24. 24.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
25. 25.🧮 Resistors of 50 Ω, 47 Ω, 330 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.🧩 Which component is a resistance knob? (a) potentiometer (b) buzzer (c) LED (d) diode
27. 27.🧩 Which component senses how hot it is? (a) fuse (b) potentiometer (c) transistor (d) thermistor
28. 28.True or false: an LED glows using little power. (a) True (b) False
29. 29.🧩 Which component glows using little power? (a) resistor (b) thermistor (c) diode (d) LED
30. 30.🧮 Resistors of 68 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
31. 31.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
32. 32.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V ÷ R (c) I = V × R (d) I = V + R
33. 33.📏 How many kilowatts (kW) is 3150 W? =
34. 34.True or false: a resistor limits the current. (a) False (b) True
35. 35.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light-emitting diode (d) light energy dial
36. 36.🧮 A 220 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
37. 37.🔺 A 12.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
38. 38.🌈 In the resistor colour code, which number does grey stand for?
39. 39.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) make light (d) measure heat
40. 40.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =

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