Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 887 · 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.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
2. 2.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = R ÷ V (d) I = V ÷ R
3. 3.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🧮 Resistors of 10 Ω, 150 Ω, 10 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
6. 6.🌈 A resistor has the colour bands white, orange, red. What is its value (in ohms)?
7. 7.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
8. 8.True or false: a diode is a resistance knob. (a) True (b) False
9. 9.💡 What does LED stand for? (a) low energy device (b) light-emitting diode (c) light energy dial (d) large electric dial
10. 10.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I ÷ R (d) V = I × R
11. 11.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
12. 12.💡 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
13. 13.🔺 A current of 1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
15. 15.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it does not light (d) it changes colour
16. 16.🧾 A family uses 50 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
17. 17.What does a resistor do? (a) beeps for an alarm (b) makes things spin (c) boosts a small signal (d) has coloured bands
18. 18.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
19. 19.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) stay the same (d) bigger
20. 20.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) always zero (d) their sum
21. 21.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
22. 22.🧮 Resistors of 220 Ω, 20 Ω, 47 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
23. 23.Which of these is measured in amperes (A)? (a) current (b) energy used each second (c) how much a part resists (d) voltage
24. 24.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
26. 26.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1300 Ω resistor? (a) brown-orange-orange (b) brown-orange-red (c) brown-orange-brown (d) orange-brown-red
28. 28.🌈 A resistor has the colour bands brown, violet, red. What is its value (in ohms)?
29. 29.🧮 A 50 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
30. 30.True or false: an LED senses how hot it is. (a) True (b) False
31. 31.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) an LED (d) a motor
32. 32.🧾 A family uses 180 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
33. 33.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.📏 Which unit measures the flow of charge? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
35. 35.🌈 In the resistor colour code, which number does blue stand for?
36. 36.🔍 Which is the odd one out? (a) leave the TV on standby (b) run fans in empty rooms (c) use LED lamps (d) use old filament bulbs
37. 37.True or false: to use daylight to read saves electricity. (a) False (b) True
38. 38.⚡ A device works on 24 V and takes 0.1 A. What is its power (in watts)? =
39. 39.What does a motor do? (a) makes a beeping sound (b) senses how bright it is (c) makes things spin (d) boosts a small signal
40. 40.📏 How many watts (W) is 1.1 kW?

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