Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 112 · 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.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to limit the current (d) to make it brighter
2. 2.🔺 A current of 2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) smaller (d) stay the same
4. 4.🌈 A resistor has the colour bands white, brown, orange. What is its value in kilo-ohms (kΩ)? =
5. 5.📏 How many kilowatts (kW) is 2600 W? =
6. 6.🌈 A resistor has the colour bands blue, grey, yellow. What is its value in kilo-ohms (kΩ)? =
7. 7.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
8. 8.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
9. 9.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) less than either one (d) their sum
12. 12.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
13. 13.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.Which of these saves electricity? (a) leave fridge door open (b) leave the TV on standby (c) set the AC to 24 °C (d) run fans in empty rooms
16. 16.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
17. 17.📏 Which unit measures voltage? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
18. 18.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it lights brighter (d) it does not light
19. 19.True or false: a buzzer makes a beeping sound. (a) False (b) True
20. 20.Which of these is measured in amperes (A)? (a) power (b) the push of a cell (c) current (d) energy used each second
21. 21.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
22. 22.Which of these is measured in amperes (A)? (a) the flow of charge (b) voltage (c) resistance (d) power
23. 23.🧮 A 5.5 V battery is joined to 12 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
24. 24.🧮 Resistors of 150 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
25. 25.True or false: to close the fridge quickly wastes electricity. (a) False (b) True
26. 26.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
27. 27.True or false: the ammeter measures current. (a) False (b) True
28. 28.📏 Which unit measures the push of a cell? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
29. 29.Which of these is measured in ohms (Ω)? (a) energy used each second (b) voltage (c) current (d) resistance
30. 30.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
31. 31.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
32. 32.⚡ A 9 W device works on 9 V. What current does it take (in amperes)? =
33. 33.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the tap handle (c) the pipe colour (d) the water tank lid
35. 35.📏 Which unit measures current? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
36. 36.True or false: a capacitor smooths a wobbly supply. (a) True (b) False
37. 37.Which of these is measured in ohms (Ω)? (a) voltage (b) current (c) how much a part resists (d) the push of a cell
38. 38.True or false: to iron one shirt at a time saves electricity. (a) True (b) False
39. 39.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets smaller (d) gets bigger
40. 40.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter

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