Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 513 · 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.Which of these is measured in ohms (Ω)? (a) current (b) resistance (c) power (d) the push of a cell
2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 490 Ω resistor? (a) white-yellow-brown (b) yellow-white-brown (c) yellow-white-red (d) yellow-white-black
3. 3.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
4. 4.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?
5. 5.🧩 Which component glows using little power? (a) diode (b) resistor (c) LED (d) fuse
6. 6.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
8. 8.💡 An LED is joined to a 3 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) lights up (c) does not light
9. 9.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 A 4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
11. 11.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
12. 12.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
13. 13.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I
14. 14.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
15. 15.🧩 Which part changes electrical energy into sound? (a) a diode (b) a buzzer (c) a resistor (d) a capacitor
16. 16.🌈 A resistor has the colour bands white, white, red. What is its value in kilo-ohms (kΩ)? =
17. 17.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
18. 18.🌈 A resistor has the colour bands orange, blue, yellow. What is its value in kilo-ohms (kΩ)? =
19. 19.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
20. 20.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
21. 21.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
22. 22.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
23. 23.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
24. 24.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it lights brighter (d) it makes a sound
25. 25.🌈 A resistor has the colour bands red, white, brown. What is its value (in ohms)?
26. 26.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
27. 27.🔺 A 60 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
28. 28.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the colour of light (d) the length of a wire
29. 29.True or false: an LED glows using little power. (a) False (b) True
30. 30.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
31. 31.💡 An LED is joined to a 3 V battery through a 470 Ω 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
32. 32.📏 How many amperes (A) is 2670 mA? =
33. 33.🧮 A 3.75 V battery is joined to 12 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
34. 34.📏 How many kilowatts (kW) is 3200 W? =
35. 35.True or false: a diode has coloured bands. (a) False (b) True
36. 36.🔺 A current of 2 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
38. 38.True or false: a buzzer makes a beeping sound. (a) True (b) False
39. 39.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 1000 (c) 10 (d) 100
40. 40.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True

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