Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 205 · 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.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = V + R (d) I = R ÷ V
2. 2.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
3. 3.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
4. 4.📏 How many kilowatts (kW) is 2000 W? =
5. 5.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
6. 6.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
8. 8.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
9. 9.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
10. 10.True or false: the voltmeter is joined in series. (a) True (b) False
11. 11.🌈 A resistor has the colour bands yellow, orange, red. What is its value in kilo-ohms (kΩ)? =
12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9500 Ω resistor? (a) white-green-orange (b) green-white-red (c) white-green-brown (d) white-green-red
13. 13.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a capacitor (d) a diode
14. 14.True or false: an LDR senses how bright it is. (a) True (b) False
15. 15.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
16. 16.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) any band (d) the gold band
18. 18.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
19. 19.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8100 Ω resistor? (a) grey-brown-red (b) grey-brown-orange (c) grey-brown-brown (d) brown-grey-red
20. 20.🌈 A resistor has the colour bands orange, violet, orange. What is its value (in ohms)?
21. 21.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 99 Ω resistor? (a) white-white-brown (b) brown-white-black (c) white-black-black (d) white-white-black
23. 23.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
24. 24.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
26. 26.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I + R (c) V = R ÷ I (d) V = I ÷ R
28. 28.🧮 A 5 V battery is joined to 2 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
29. 29.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🔍 Which is the odd one out? (a) close the fridge quickly (b) switch off empty rooms (c) run fans in empty rooms (d) use daylight to read
31. 31.🔺 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
32. 32.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
33. 33.📏 How many amperes (A) is 1480 mA? =
34. 34.🌈 A resistor has the colour bands red, white, red. What is its value in kilo-ohms (kΩ)? =
35. 35.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to change its colour (d) to limit the current
36. 36.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
37. 37.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
39. 39.🧩 Which component beeps for an alarm? (a) diode (b) LDR (c) buzzer (d) resistor
40. 40.🧮 A 2.4 V battery is joined to 6 Ω and 6 Ω resistors in series. What current flows (in amperes)? =

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