Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 49 · 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 current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
2. 2.⚡ A 3 W device works on 1.5 V. What current does it take (in amperes)? =
3. 3.⚡ A device works on 12 V and takes 0.25 A. What is its power (in watts)? =
4. 4.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
5. 5.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
6. 6.🧩 Which component makes a beeping sound? (a) capacitor (b) LED (c) potentiometer (d) buzzer
7. 7.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = V × I (d) P = I ÷ V
8. 8.🌈 A resistor has the colour bands grey, black, brown. What is its value (in ohms)?
9. 9.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the pipe colour (c) the water pressure (d) the water tank lid
10. 10.🔺 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
11. 11.What does a fuse do? (a) makes a beeping sound (b) blows if current is high (c) stores a little charge (d) lets current go one way
12. 12.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
13. 13.🔺 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
14. 14.📏 How many milliamperes (mA) is 2.6 A?
15. 15.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
16. 16.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
17. 17.True or false: the flow of charge is measured in watts (W). (a) True (b) False
18. 18.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
19. 19.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A current of 2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🔺 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
23. 23.🔺 A current of 0.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
24. 24.True or false: an LDR makes things spin. (a) False (b) True
25. 25.Which of these saves electricity? (a) switch off empty rooms (b) run fans in empty rooms (c) leave fridge door open (d) leave the TV on standby
26. 26.🌈 A resistor has the colour bands grey, yellow, orange. What is its value in kilo-ohms (kΩ)? =
27. 27.🔺 A current of 2.5 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
28. 28.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
29. 29.Which of these saves electricity? (a) run fans in empty rooms (b) use old filament bulbs (c) leave fridge door open (d) use daylight to read
30. 30.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
31. 31.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the pipe colour (c) the flow of water (d) a narrow pipe
32. 32.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
33. 33.True or false: to iron one shirt at a time saves electricity. (a) False (b) True
34. 34.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
35. 35.📏 How many milliamperes (mA) is 1.86 A?
36. 36.🧮 Resistors of 33 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to make it brighter (d) to limit the current
38. 38.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
39. 39.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
40. 40.🔺 A current of 40 mA flows when 13.2 V is joined across a resistor. What is its resistance (in ohms)?

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