Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 389 · 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.Which of these is measured in amperes (A)? (a) how much a part resists (b) the flow of charge (c) power (d) energy used each second
2. 2.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 25 % (d) 50 %
3. 3.Which of these is measured in watts (W)? (a) the flow of charge (b) current (c) the push of a cell (d) energy used each second
4. 4.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets smaller (d) gets bigger
5. 5.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
6. 6.🔺 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
7. 7.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to change its colour (d) to make it brighter
8. 8.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the flow of water (d) the pipe colour
9. 9.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🔺 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
12. 12.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🌈 A resistor has the colour bands brown, brown, black. What is its value (in ohms)?
14. 14.🔺 A 12 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
15. 15.📏 Which unit measures resistance? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
16. 16.🧮 A 0.8 V battery is joined to 6 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
17. 17.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it does not light (c) it changes colour (d) it makes a sound
18. 18.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
19. 19.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
20. 20.🧮 Resistors of 150 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
21. 21.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 ampere (c) 1 watt (d) 1 kilowatt-hour (kWh)
22. 22.⚡ A device works on 1.5 V and takes 2 A. What is its power (in watts)? =
23. 23.🔺 A current of 0.1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) zero (d) smaller
25. 25.True or false: power is measured in watts (W). (a) True (b) False
26. 26.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
27. 27.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) energy used each second (d) the size of a cell
28. 28.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
29. 29.🧮 Resistors of 22 Ω, 20 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
30. 30.🧩 Which component smooths a wobbly supply? (a) capacitor (b) LED (c) motor (d) resistor
31. 31.🔺 A current of 0.25 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
32. 32.📏 How many kilo-ohms (kΩ) is 1500 Ω? =
33. 33.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
34. 34.True or false: a buzzer beeps for an alarm. (a) True (b) False
35. 35.📏 How many kilowatts (kW) is 550 W? =
36. 36.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
37. 37.⚡ A device works on 6 V and takes 2 A. What is its power (in watts)? =
38. 38.True or false: to run fans in empty rooms saves electricity. (a) True (b) False
39. 39.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
40. 40.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?

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