Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 952 · 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 current of 0.25 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) any band (d) the gold band
3. 3.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
4. 4.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to store charge (d) to make it brighter
5. 5.🌈 In the resistor colour code, which number does blue stand for?
6. 6.What does a thermistor do? (a) turns a fan or wheels (b) stores a little charge (c) senses how hot it is (d) smooths a wobbly supply
7. 7.🧩 Which component stores a little charge? (a) capacitor (b) diode (c) LDR (d) thermistor
8. 8.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
9. 9.🧮 A 220 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
10. 10.What does a capacitor do? (a) glows using little power (b) boosts a small signal (c) makes a beeping sound (d) stores a little charge
11. 11.📏 How many kilo-ohms (kΩ) is 4700 Ω? =
12. 12.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
13. 13.🔺 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
14. 14.🔺 A current of 40 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I ÷ R (c) V = R ÷ I (d) V = I + R
16. 16.📏 Which unit measures power? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
17. 17.🌈 A resistor has the colour bands red, yellow, yellow. What is its value in kilo-ohms (kΩ)? =
18. 18.🌈 In the resistor colour code, which number does violet stand for?
19. 19.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
20. 20.💡 A red LED uses 2 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
21. 21.🔺 A 15 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
22. 22.True or false: a motor turns a fan or wheels. (a) False (b) True
23. 23.🧩 Which component glows using little power? (a) LED (b) buzzer (c) fuse (d) thermistor
24. 24.🧾 A family uses 50 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
25. 25.🧮 A 3.5 V battery is joined to 5 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
26. 26.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) stay the same (d) smaller
27. 27.🧮 A 68 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
28. 28.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
30. 30.What does a transistor do? (a) boosts a small signal (b) smooths a wobbly supply (c) limits the current (d) has coloured bands
31. 31.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
33. 33.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 watt
34. 34.True or false: a potentiometer limits the current. (a) False (b) True
35. 35.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 47 Ω resistor? (a) violet-yellow-black (b) yellow-violet-black (c) yellow-violet-brown (d) green-violet-black
37. 37.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
39. 39.What does a buzzer do? (a) smooths a wobbly supply (b) lets current go one way (c) turns a fan or wheels (d) makes a beeping sound
40. 40.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

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