Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 747 · 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.💡 An LED is joined to a 5 V battery through a 1000 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
2. 2.🔺 An 8.25 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 32000 Ω resistor? (a) orange-red-yellow (b) red-orange-orange (c) orange-red-red (d) orange-red-orange
4. 4.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an LED lamp (d) an oil lamp
5. 5.📏 How many amperes (A) is 400 mA? =
6. 6.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V × I (d) R = V + I
7. 7.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I + R (d) V = I ÷ R
8. 8.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the widest gap (d) the gold band
9. 9.🧮 An 8.5 V battery is joined to 12 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
10. 10.🧮 Resistors of 33 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.What does a resistor do? (a) is a resistance knob (b) makes a beeping sound (c) makes things spin (d) has coloured bands
13. 13.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
14. 14.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to change its colour (d) to store charge
15. 15.📏 How many watts (W) is 3.6 kW?
16. 16.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
17. 17.💡 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) lights up (b) does not light (c) may burn out
18. 18.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) energy used each second (d) the length of a wire
19. 19.What does a fuse do? (a) has coloured bands (b) lets current go one way (c) makes a beeping sound (d) blows if current is high
20. 20.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
22. 22.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
23. 23.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
24. 24.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
25. 25.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
26. 26.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
27. 27.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
28. 28.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
29. 29.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = R ÷ V (c) I = V + R (d) I = V ÷ R
30. 30.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
32. 32.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
33. 33.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) a narrow pipe (c) the flow of water (d) the water pressure
34. 34.Which of these saves electricity? (a) leave fridge door open (b) run fans in empty rooms (c) use daylight to read (d) leave the TV on standby
35. 35.🧾 A 250 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
36. 36.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
37. 37.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
38. 38.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the water pressure (c) the pipe colour (d) the tap handle
39. 39.🌈 A resistor has the colour bands orange, orange, orange. What is its value in kilo-ohms (kΩ)? =
40. 40.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?

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