Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 742 · 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: on an LED, the shorter leg is the anode (+). (a) True (b) False
2. 2.Which of these saves electricity? (a) use old filament bulbs (b) iron one shirt at a time (c) use daylight to read (d) leave fridge door open
3. 3.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
4. 4.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
5. 5.🧮 Resistors of 10 Ω, 68 Ω, 47 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
6. 6.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
7. 7.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
8. 8.🌈 In the resistor colour code, which number does black stand for?
9. 9.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
10. 10.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
11. 11.📏 How many milliamperes (mA) is 0.66 A?
12. 12.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) spin a wheel (d) measure heat
13. 13.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
14. 14.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
15. 15.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1024 (c) 1000 (d) 10
16. 16.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) lights up (c) does not light
17. 17.🧩 Which component makes things spin? (a) LED (b) capacitor (c) motor (d) LDR
18. 18.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) an LED (d) a motor
19. 19.🧩 Which component senses how bright it is? (a) motor (b) thermistor (c) diode (d) LDR
20. 20.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
21. 21.Which of these is measured in volts (V)? (a) current (b) voltage (c) how much a part resists (d) the flow of charge
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 660 Ω resistor? (a) blue-blue-brown (b) blue-violet-brown (c) blue-blue-red (d) blue-blue-black
23. 23.🧩 Which component boosts a small signal? (a) fuse (b) transistor (c) resistor (d) buzzer
24. 24.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🧩 Which component limits the current? (a) fuse (b) motor (c) capacitor (d) resistor
26. 26.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) the water pressure (c) the pipe colour (d) a narrow pipe
27. 27.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
28. 28.🔺 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
29. 29.True or false: the ammeter is joined across a part. (a) True (b) False
30. 30.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to store charge (d) to change its colour
31. 31.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V ÷ I (d) R = V + I
32. 32.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
34. 34.🧮 Resistors of 22 Ω, 100 Ω, 50 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
35. 35.🧮 A 3.25 V battery is joined to 10 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
36. 36.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
37. 37.📏 Which unit measures resistance? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
38. 38.📏 How many watts (W) is 0.1 kW?
39. 39.📏 Which unit measures the push of a cell? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
40. 40.🌈 A resistor has the colour bands violet, brown, orange. What is its value (in ohms)?

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