Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 577 · 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 50 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
2. 2.💡 An LED is joined to a 6 V battery through a 470 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
3. 3.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
4. 4.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = R ÷ V (d) I = V ÷ R
5. 5.📏 How many milliamperes (mA) is 1.69 A?
6. 6.🔺 A 50 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
7. 7.🔺 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
8. 8.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
9. 9.🌈 In the resistor colour code, which number does red stand for?
10. 10.🌈 A resistor has the colour bands yellow, brown, red. What is its value in kilo-ohms (kΩ)? =
11. 11.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
12. 12.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an oil lamp (d) an LED lamp
14. 14.🧩 Which component beeps for an alarm? (a) motor (b) resistor (c) thermistor (d) buzzer
15. 15.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
16. 16.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 30 Ω resistor? (a) orange-black-black (b) yellow-black-black (c) yellow-orange-black (d) orange-black-brown
18. 18.🧾 A 1000 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
19. 19.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
21. 21.📏 Which unit measures the flow of charge? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
22. 22.🌈 A resistor has the colour bands yellow, green, yellow. What is its value in kilo-ohms (kΩ)? =
23. 23.📏 How many kilo-ohms (kΩ) is 9200 Ω? =
24. 24.🌈 A resistor has the colour bands brown, green, orange. What is its value (in ohms)?
25. 25.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
26. 26.🧮 Resistors of 470 Ω, 10 Ω, 10 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
27. 27.🔺 A current of 2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🧮 A 6 V battery is joined to 4 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
29. 29.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light-emitting diode (d) light energy dial
30. 30.🧾 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?
31. 31.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
32. 32.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell
33. 33.📏 How many amperes (A) is 1100 mA? =
34. 34.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I × R (c) V = R ÷ I (d) V = I ÷ R
35. 35.🔺 A current of 40 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
36. 36.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) smaller (d) zero
37. 37.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the water pressure (c) the tap handle (d) the pipe colour
38. 38.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a buzzer (d) a capacitor
39. 39.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.🔺 A 5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?

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