Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 206 · 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.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 890 Ω resistor? (a) white-grey-brown (b) grey-white-brown (c) grey-white-red (d) grey-white-black
3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9700 Ω resistor? (a) white-violet-red (b) white-violet-brown (c) white-violet-orange (d) violet-white-red
4. 4.📏 How many watts (W) is 0.9 kW?
5. 5.True or false: voltage is measured in watts (W). (a) False (b) True
6. 6.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
7. 7.True or false: a capacitor stores a little charge. (a) False (b) True
8. 8.📏 Which unit measures voltage? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
9. 9.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
10. 10.💡 A red LED uses 2 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
11. 11.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to change its colour (d) to store charge
12. 12.True or false: a motor makes things spin. (a) True (b) False
13. 13.🌈 A resistor has the colour bands grey, white, orange. What is its value in kilo-ohms (kΩ)? =
14. 14.🔍 Which is the odd one out? (a) run fans in empty rooms (b) switch off empty rooms (c) use LED lamps (d) set the AC to 24 °C
15. 15.📏 How many ohms (Ω) is 4.8 kΩ?
16. 16.📏 How many watts (W) is 4.6 kW?
17. 17.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.🧮 Resistors of 20 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
19. 19.🔺 A current of 20 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.🔺 A current of 1 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.True or false: a motor senses how hot it is. (a) False (b) True
22. 22.🔺 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
23. 23.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
24. 24.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) store charge briefly (d) spin a wheel
25. 25.True or false: the ammeter measures voltage. (a) False (b) True
26. 26.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets smaller (d) gets bigger
27. 27.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
28. 28.What does an LDR do? (a) senses how bright it is (b) blows if current is high (c) makes a beeping sound (d) glows using little power
29. 29.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
30. 30.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 600 Ω resistor? (a) blue-black-red (b) violet-blue-brown (c) blue-black-black (d) blue-black-brown
32. 32.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.True or false: the ammeter is joined across a part. (a) True (b) False
34. 34.🔺 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
35. 35.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🧾 A family uses 80 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
37. 37.Which of these saves electricity? (a) leave fridge door open (b) iron one shirt at a time (c) use daylight to read (d) leave the TV on standby
38. 38.⚡ A 12 W device works on 12 V. What current does it take (in amperes)? =
39. 39.🔺 A 45 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
40. 40.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =

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