Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 715 · 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: resistance is measured in ohms (Ω). (a) False (b) True
2. 2.📏 How many ohms (Ω) is 2.3 kΩ?
3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 34000 Ω resistor? (a) orange-yellow-yellow (b) orange-yellow-red (c) orange-yellow-orange (d) yellow-orange-orange
4. 4.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) more than either one (d) their sum
5. 5.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the size of a cell (d) the length of a wire
7. 7.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
8. 8.🧮 A 10 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)?
9. 9.🧩 Which component senses how hot it is? (a) diode (b) potentiometer (c) motor (d) thermistor
10. 10.🔺 A 9.4 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
11. 11.True or false: to set the AC to 24 °C saves electricity. (a) True (b) False
12. 12.What does a resistor do? (a) turns a fan or wheels (b) glows using little power (c) has coloured bands (d) senses how hot it is
13. 13.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
14. 14.🌈 A resistor has the colour bands white, brown, brown. What is its value (in ohms)?
15. 15.🌈 A resistor has the colour bands brown, black, red. What is its value (in ohms)?
16. 16.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
17. 17.📏 How many amperes (A) is 1960 mA? =
18. 18.🔍 Which is the odd one out? (a) run fans in empty rooms (b) use daylight to read (c) switch off empty rooms (d) close the fridge quickly
19. 19.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) measure heat (d) spin a wheel
20. 20.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
21. 21.True or false: to switch off empty rooms saves electricity. (a) True (b) False
22. 22.True or false: to close the fridge quickly wastes electricity. (a) False (b) True
23. 23.🌈 In the resistor colour code, which number does brown stand for?
24. 24.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 1000 (c) 10 (d) 100
25. 25.Which of these is measured in ohms (Ω)? (a) power (b) current (c) the flow of charge (d) resistance
26. 26.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) any band (d) the gold band
27. 27.🔺 A 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
28. 28.📏 How many amperes (A) is 970 mA? =
29. 29.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
30. 30.🌈 A resistor has the colour bands blue, blue, orange. What is its value in kilo-ohms (kΩ)? =
31. 31.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it changes colour (d) it lights brighter
32. 32.📏 How many amperes (A) is 1150 mA? =
33. 33.True or false: a motor makes things spin. (a) False (b) True
34. 34.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) a candle (d) an oil lamp
35. 35.📏 How many watts (W) is 1.3 kW?
36. 36.🌈 A resistor has the colour bands red, red, red. What is its value (in ohms)?
37. 37.🌈 A resistor has the colour bands red, blue, brown. What is its value (in ohms)?
38. 38.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 volt
39. 39.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
40. 40.Which of these wastes electricity? (a) unplug idle chargers (b) use old filament bulbs (c) set the AC to 24 °C (d) close the fridge quickly

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