Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 133 · 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 resistor colour code, which number does violet stand for?
2. 2.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
3. 3.🌈 A resistor has the colour bands brown, brown, red. What is its value in kilo-ohms (kΩ)? =
4. 4.🔺 A 7.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
5. 5.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an LED lamp (d) an oil lamp
6. 6.🌈 A resistor has the colour bands grey, green, black. What is its value (in ohms)?
7. 7.🧩 Which component lets current go one way? (a) diode (b) potentiometer (c) LED (d) capacitor
8. 8.Which of these wastes electricity? (a) switch off empty rooms (b) close the fridge quickly (c) use old filament bulbs (d) use daylight to read
9. 9.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
10. 10.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) less than either one (d) more than either one
11. 11.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 watt
12. 12.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
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) lights up (b) does not light (c) may burn out
14. 14.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
15. 15.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) how much a part resists (c) power (d) voltage
16. 16.🧩 Which component smooths a wobbly supply? (a) diode (b) LDR (c) capacitor (d) buzzer
17. 17.🌈 A resistor has the colour bands blue, grey, orange. What is its value in kilo-ohms (kΩ)? =
18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 50 % (d) 25 %
19. 19.🧮 A 220 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
20. 20.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) does not light (b) may burn out (c) lights up
21. 21.True or false: the flow of charge is measured in ohms (Ω). (a) True (b) False
22. 22.🔺 A 5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
23. 23.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
24. 24.Which of these is measured in amperes (A)? (a) power (b) current (c) the push of a cell (d) resistance
25. 25.🔺 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
26. 26.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
28. 28.True or false: a motor turns a fan or wheels. (a) False (b) True
29. 29.True or false: power is measured in watts (W). (a) True (b) False
30. 30.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
31. 31.🧩 Which component makes a beeping sound? (a) resistor (b) fuse (c) potentiometer (d) buzzer
32. 32.📏 How many ohms (Ω) is 6.6 kΩ?
33. 33.📏 How many ohms (Ω) is 7.5 kΩ?
34. 34.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
35. 35.🧩 Which component senses how bright it is? (a) resistor (b) capacitor (c) LDR (d) buzzer
36. 36.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
37. 37.🌈 In the resistor colour code, which number does white stand for?
38. 38.True or false: resistance is measured in watts (W). (a) True (b) False
39. 39.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
40. 40.📏 How many watts (W) is 4.5 kW?

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