Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 927 · 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 resistor has the colour bands white, orange, orange. What is its value in kilo-ohms (kΩ)? =
2. 2.Which of these is measured in volts (V)? (a) current (b) resistance (c) energy used each second (d) voltage
3. 3.📏 How many milliamperes (mA) is 2.69 A?
4. 4.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
5. 5.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
6. 6.Which of these saves electricity? (a) switch off empty rooms (b) iron one shirt at a time (c) run fans in empty rooms (d) leave the TV on standby
7. 7.🧾 A 500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
8. 8.🧮 An 8.5 V battery is joined to 5 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
9. 9.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
10. 10.💡 An LED is joined to a 12 V battery with no 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
11. 11.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
12. 12.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) stays the same (d) gets bigger
14. 14.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 4.25 V supply. What current flows (in mA)?
15. 15.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
16. 16.📏 Which unit measures how much a part resists? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
17. 17.🔺 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
18. 18.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
19. 19.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 60 (c) 100 (d) 10
20. 20.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
21. 21.🧮 A 3.25 V battery is joined to 10 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
22. 22.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = I ÷ V (d) P = V ÷ I
23. 23.🔺 A current of 0.25 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.True or false: a buzzer beeps for an alarm. (a) False (b) True
25. 25.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
26. 26.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.Which of these is measured in volts (V)? (a) energy used each second (b) power (c) the flow of charge (d) the push of a cell
28. 28.💡 An LED is joined to a 6 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) may burn out (c) does not light
29. 29.💡 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?
30. 30.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
31. 31.⚡ A 9 W device works on 3 V. What current does it take (in amperes)? =
32. 32.🌈 A resistor has the colour bands orange, orange, orange. What is its value in kilo-ohms (kΩ)? =
33. 33.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.🔺 A current of 40 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a fuse (d) a motor
37. 37.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
38. 38.🌈 In the resistor colour code, which number does brown stand for?
39. 39.⚡ A 36 W device works on 24 V. What current does it take (in amperes)? =
40. 40.📏 How many amperes (A) is 2010 mA? =

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