Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 460 · 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.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
2. 2.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 100 (c) 10 (d) 1000
3. 3.📏 How many milliamperes (mA) is 1.25 A?
4. 4.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) becomes zero (d) gets smaller
5. 5.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
6. 6.Which of these is measured in volts (V)? (a) the push of a cell (b) current (c) energy used each second (d) the flow of charge
7. 7.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1024 (c) 1000 (d) 10
8. 8.🌈 A resistor has the colour bands white, black, brown. What is its value (in ohms)?
9. 9.📏 Which unit measures how much a part resists? (a) volt (V) (b) ohm (Ω) (c) watt (W) (d) ampere (A)
10. 10.🔺 A current of 0.25 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
11. 11.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
13. 13.🌈 In the resistor colour code, which number does black stand for?
14. 14.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the pipe colour (c) the water pressure (d) the tap handle
16. 16.Which of these saves electricity? (a) iron one shirt at a time (b) set the AC to 24 °C (c) leave fridge door open (d) use old filament bulbs
17. 17.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.🔺 A 3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
19. 19.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 41 Ω resistor? (a) yellow-brown-black (b) brown-yellow-black (c) yellow-brown-brown (d) green-brown-black
20. 20.⚡ A 27 W device works on 9 V. What current does it take (in amperes)? =
21. 21.True or false: the flow of charge is measured in amperes (A). (a) True (b) False
22. 22.🧮 A 1.25 V battery is joined to 3 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
23. 23.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) the widest gap (d) any band
25. 25.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
26. 26.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
27. 27.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) energy used each second (d) the colour of light
28. 28.What does a resistor do? (a) makes things spin (b) lets current go one way (c) smooths a wobbly supply (d) limits the current
29. 29.Which of these wastes electricity? (a) set the AC to 24 °C (b) switch off empty rooms (c) unplug idle chargers (d) leave the TV on standby
30. 30.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 watt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
31. 31.💡 An LED is joined to a 9 V battery through a 330 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
32. 32.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
33. 33.📏 How many ohms (Ω) is 3.7 kΩ?
34. 34.📏 How many milliamperes (mA) is 0.13 A?
35. 35.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
37. 37.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.📏 How many amperes (A) is 1480 mA? =
39. 39.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = I + R (d) V = R ÷ I
40. 40.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V + R (c) I = V × R (d) I = R ÷ V

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