Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 520 · 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.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
2. 2.📏 Which unit measures the flow of charge? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
3. 3.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
4. 4.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
5. 5.📏 How many kilowatts (kW) is 4700 W? =
6. 6.🔺 A current of 1.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🧮 Resistors of 20 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
8. 8.📏 How many amperes (A) is 360 mA? =
9. 9.🧮 A 10 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
10. 10.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
12. 12.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 790 Ω resistor? (a) violet-white-red (b) white-violet-brown (c) violet-white-brown (d) violet-white-black
14. 14.🌈 A resistor has the colour bands grey, violet, yellow. What is its value in kilo-ohms (kΩ)? =
15. 15.🧮 A 1.6 V battery is joined to 6 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
16. 16.What does a thermistor do? (a) senses how hot it is (b) turns a fan or wheels (c) blows if current is high (d) senses how bright it is
17. 17.🌈 In the resistor colour code, which number does white stand for?
18. 18.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
19. 19.True or false: a buzzer makes a beeping sound. (a) False (b) True
20. 20.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) the gold band (d) any band
22. 22.🔍 Which is the odd one out? (a) leave the TV on standby (b) switch off empty rooms (c) use daylight to read (d) set the AC to 24 °C
23. 23.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
24. 24.True or false: a resistor makes things spin. (a) True (b) False
25. 25.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🧾 A 250 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
27. 27.🧮 A 470 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
28. 28.🔺 A 10 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
29. 29.⚡ A device works on 6 V and takes 1.5 A. What is its power (in watts)? =
30. 30.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
31. 31.Which of these saves electricity? (a) set the AC to 24 °C (b) run fans in empty rooms (c) iron one shirt at a time (d) use old filament bulbs
32. 32.💡 What does LED stand for? (a) light-emitting diode (b) low energy device (c) large electric dial (d) light energy dial
33. 33.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
34. 34.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
35. 35.📏 How many amperes (A) is 50 mA? =
36. 36.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
37. 37.🔺 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
38. 38.🌈 In the resistor colour code, which number does orange stand for?
39. 39.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.🔺 A 45 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =

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