Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 478 · 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.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
2. 2.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
3. 3.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.True or false: resistance is measured in volts (V). (a) True (b) False
5. 5.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
6. 6.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
7. 7.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water tank lid (c) the pipe colour (d) the water pressure
8. 8.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
9. 9.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
10. 10.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
11. 11.🔺 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
12. 12.🌈 In the resistor colour code, which number does red stand for?
13. 13.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = V × I (d) R = I ÷ V
15. 15.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
16. 16.🔺 A current of 2.5 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
18. 18.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
19. 19.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave fridge door open (c) unplug idle chargers (d) run fans in empty rooms
20. 20.💡 What does LED stand for? (a) light energy dial (b) light-emitting diode (c) large electric dial (d) low energy device
21. 21.📏 Which unit measures how much a part resists? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 21 Ω resistor? (a) red-brown-black (b) brown-red-black (c) orange-brown-black (d) red-brown-brown
23. 23.🧮 A 150 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)?
24. 24.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an oil lamp (d) an LED lamp
25. 25.🌈 In the resistor colour code, which number does white stand for?
26. 26.💡 An LED is joined to a 5 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
27. 27.🌈 A resistor has the colour bands yellow, red, brown. What is its value (in ohms)?
28. 28.📏 How many kilo-ohms (kΩ) is 7300 Ω? =
29. 29.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the size of a cell (d) the length of a wire
30. 30.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
31. 31.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.📏 How many milliamperes (mA) is 0.97 A?
33. 33.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) gets smaller (d) becomes zero
34. 34.True or false: the push of a cell is measured in volts (V). (a) True (b) False
35. 35.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 50 % (d) 25 %
36. 36.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
37. 37.What does an LED do? (a) limits the current (b) glows using little power (c) turns a fan or wheels (d) has coloured bands
38. 38.🧮 Resistors of 22 Ω, 50 Ω, 150 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
39. 39.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.🔺 A current of 2.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =

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