Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 219 · 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 ohms (Ω)? (a) power (b) energy used each second (c) voltage (d) how much a part resists
2. 2.🔺 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
3. 3.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
4. 4.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
5. 5.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🔍 Which is the odd one out? (a) switch off empty rooms (b) close the fridge quickly (c) unplug idle chargers (d) run fans in empty rooms
7. 7.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V ÷ I (d) R = V + I
8. 8.🌈 In the resistor colour code, which number does green stand for?
9. 9.🧾 A 100 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
10. 10.⚡ A 2.5 W device works on 5 V. What current does it take (in amperes)? =
11. 11.What does an LDR do? (a) senses how bright it is (b) limits the current (c) has coloured bands (d) senses how hot it is
12. 12.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it changes colour (d) it does not light
13. 13.🔺 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
14. 14.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🌈 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
16. 16.🔺 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
17. 17.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
18. 18.🔺 A 30 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
19. 19.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) an LED lamp (d) a filament bulb
22. 22.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the colour of light (d) the length of a wire
23. 23.Which of these is measured in volts (V)? (a) how much a part resists (b) current (c) the push of a cell (d) the flow of charge
24. 24.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
25. 25.🧩 Which component makes a beeping sound? (a) buzzer (b) LED (c) resistor (d) motor
26. 26.Which of these is measured in amperes (A)? (a) energy used each second (b) how much a part resists (c) current (d) power
27. 27.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 410 Ω resistor? (a) yellow-brown-black (b) brown-yellow-brown (c) yellow-brown-red (d) yellow-brown-brown
29. 29.True or false: a potentiometer is a resistance knob. (a) True (b) False
30. 30.📏 Which unit measures the push of a cell? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
31. 31.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
32. 32.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
33. 33.🧮 A 330 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
34. 34.True or false: the ammeter measures current. (a) True (b) False
35. 35.🔺 A 2 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
36. 36.🧮 Resistors of 47 Ω, 470 Ω, 470 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
37. 37.🔺 A current of 3 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.True or false: an LDR has coloured bands. (a) True (b) False
39. 39.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
40. 40.What does an LED do? (a) senses how hot it is (b) stores a little charge (c) glows using little power (d) lets current go one way

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