Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 20 · 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.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
2. 2.⚡ A device works on 6 V and takes 3 A. What is its power (in watts)? =
3. 3.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
4. 4.🌈 A resistor has the colour bands violet, yellow, brown. What is its value (in ohms)?
5. 5.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.🔍 Which is the odd one out? (a) use LED lamps (b) use old filament bulbs (c) leave the TV on standby (d) iron one shirt at a time
8. 8.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
9. 9.🌈 A resistor has the colour bands white, yellow, red. What is its value in kilo-ohms (kΩ)? =
10. 10.🔺 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
11. 11.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
12. 12.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
13. 13.📏 Which unit measures power? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
14. 14.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
15. 15.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
16. 16.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🧾 A 1000 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
18. 18.🌈 In the resistor colour code, which number does grey stand for?
19. 19.🧾 A family uses 30 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
20. 20.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 60 Ω resistor? (a) violet-black-black (b) blue-black-black (c) blue-black-brown (d) violet-blue-black
22. 22.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the colour of light (d) the size of a cell
23. 23.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V + I (d) R = V × I
24. 24.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) bigger (d) smaller
25. 25.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
26. 26.🌈 In the resistor colour code, which number does orange stand for?
27. 27.True or false: a resistor stores a little charge. (a) False (b) True
28. 28.🌈 A resistor has the colour bands blue, grey, red. What is its value in kilo-ohms (kΩ)? =
29. 29.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
30. 30.📏 How many kilo-ohms (kΩ) is 4300 Ω? =
31. 31.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) spin a wheel (d) make light
32. 32.🌈 A resistor has the colour bands red, violet, orange. What is its value in kilo-ohms (kΩ)? =
33. 33.🌈 In the resistor colour code, which number does green stand for?
34. 34.🔍 Which is the odd one out? (a) close the fridge quickly (b) use LED lamps (c) use old filament bulbs (d) use daylight to read
35. 35.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.🔺 A 4 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
37. 37.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) an LED lamp (c) a candle (d) a filament bulb
38. 38.🧮 Resistors of 470 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
39. 39.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
40. 40.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter

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