Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 846 · 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.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
2. 2.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
3. 3.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
4. 4.What does a transistor do? (a) has coloured bands (b) limits the current (c) makes a beeping sound (d) boosts a small signal
5. 5.🌈 In the resistor colour code, which number does red stand for?
6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 0 % (d) 50 %
7. 7.🔺 A 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
8. 8.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V + R (c) I = V ÷ R (d) I = V × R
9. 9.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
10. 10.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
11. 11.True or false: the voltmeter is joined across a part. (a) True (b) False
12. 12.What does an LDR do? (a) has coloured bands (b) makes a beeping sound (c) glows using little power (d) senses how bright it is
13. 13.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) lights up (c) does not light
14. 14.🌈 A resistor has the colour bands violet, orange, orange. What is its value (in ohms)?
15. 15.🧮 A 1.6 V battery is joined to 6 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
16. 16.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
17. 17.🌈 A resistor has the colour bands orange, violet, orange. What is its value (in ohms)?
18. 18.📏 How many milliamperes (mA) is 2.62 A?
19. 19.True or false: to iron one shirt at a time saves electricity. (a) True (b) False
20. 20.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
21. 21.📏 How many kilo-ohms (kΩ) is 2300 Ω? =
22. 22.🔺 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
23. 23.Which of these wastes electricity? (a) unplug idle chargers (b) close the fridge quickly (c) use daylight to read (d) run fans in empty rooms
24. 24.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
25. 25.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
26. 26.🔺 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
27. 27.🔺 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
28. 28.🧾 A 50 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
29. 29.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
30. 30.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
31. 31.Which of these saves electricity? (a) iron one shirt at a time (b) leave the TV on standby (c) run fans in empty rooms (d) close the fridge quickly
32. 32.True or false: a buzzer beeps for an alarm. (a) False (b) True
33. 33.🌈 A resistor has the colour bands yellow, brown, orange. What is its value in kilo-ohms (kΩ)? =
34. 34.🔺 A current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🧩 Which component makes a beeping sound? (a) fuse (b) buzzer (c) motor (d) capacitor
36. 36.True or false: to close the fridge quickly saves electricity. (a) False (b) True
37. 37.🧩 Which component smooths a wobbly supply? (a) fuse (b) capacitor (c) resistor (d) LED
38. 38.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) low energy device (d) light energy dial
39. 39.🌈 A resistor has the colour bands red, grey, orange. What is its value (in ohms)?
40. 40.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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