Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 633 · 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.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
2. 2.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
3. 3.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) a bigger tank (c) a narrow pipe (d) the flow of water
4. 4.What does a fuse do? (a) has coloured bands (b) blows if current is high (c) makes things spin (d) is a resistance knob
5. 5.🧮 Resistors of 470 Ω, 22 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
6. 6.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light energy dial (d) light-emitting diode
7. 7.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
8. 8.🔺 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
9. 9.True or false: the ammeter measures current. (a) False (b) True
10. 10.⚡ A 24 W device works on 12 V. What current does it take (in amperes)? =
11. 11.🧾 A family uses 70 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
12. 12.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
14. 14.🔍 Which is the odd one out? (a) leave fridge door open (b) use daylight to read (c) switch off empty rooms (d) set the AC to 24 °C
15. 15.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
16. 16.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
18. 18.🌈 A resistor has the colour bands grey, blue, black. What is its value (in ohms)?
19. 19.🔺 A 24 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
20. 20.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) bigger (d) stay the same
21. 21.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %
22. 22.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 60 (c) 100 (d) 1000
24. 24.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 53 Ω resistor? (a) green-orange-black (b) orange-green-black (c) green-orange-brown (d) blue-orange-black
25. 25.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
26. 26.True or false: to iron one shirt at a time saves electricity. (a) True (b) False
27. 27.🌈 In the resistor colour code, which number does red stand for?
28. 28.🔺 A current of 2.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.True or false: a transistor glows using little power. (a) False (b) True
30. 30.📏 Which unit measures the push of a cell? (a) volt (V) (b) ohm (Ω) (c) watt (W) (d) ampere (A)
31. 31.True or false: how much a part resists is measured in watts (W). (a) True (b) False
32. 32.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) always zero (d) less than either one
33. 33.What does a buzzer do? (a) smooths a wobbly supply (b) makes a beeping sound (c) stores a little charge (d) limits the current
34. 34.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.🧮 A 220 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
36. 36.🧩 Which component boosts a small signal? (a) motor (b) buzzer (c) LDR (d) transistor
37. 37.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
38. 38.🧩 Which component senses how bright it is? (a) diode (b) LDR (c) resistor (d) transistor
39. 39.🔺 A current of 0.1 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.⚡ A device works on 12 V and takes 0.5 A. What is its power (in watts)? =

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