Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 967 · 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.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I + R (d) V = I × R
2. 2.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 60 (c) 100 (d) 1000
3. 3.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
4. 4.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V × R (d) I = V ÷ R
5. 5.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
6. 6.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
7. 7.🔺 A current of 1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.📏 How many amperes (A) is 1660 mA? =
9. 9.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
11. 11.⚡ A 1 W device works on 5 V. What current does it take (in amperes)? =
12. 12.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
14. 14.🔍 Which is the odd one out? (a) switch off empty rooms (b) set the AC to 24 °C (c) run fans in empty rooms (d) use daylight to read
15. 15.🔺 A 3 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
16. 16.🌈 A resistor has the colour bands violet, grey, red. What is its value (in ohms)?
17. 17.🌈 A resistor has the colour bands brown, violet, red. What is its value in kilo-ohms (kΩ)? =
18. 18.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 13 Ω resistor? (a) brown-orange-black (b) red-orange-black (c) brown-orange-brown (d) orange-brown-black
20. 20.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
21. 21.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🧾 A family uses 170 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
23. 23.📏 Which unit measures the push of a cell? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
24. 24.⚡ A 6 W device works on 12 V. What current does it take (in amperes)? =
25. 25.What does a potentiometer do? (a) limits the current (b) boosts a small signal (c) is a resistance knob (d) has coloured bands
26. 26.🧮 Resistors of 47 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
27. 27.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🔺 A current of 1 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to store charge (d) to change its colour
30. 30.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = I ÷ V (d) R = V + I
31. 31.What does an LDR do? (a) beeps for an alarm (b) makes a beeping sound (c) senses how bright it is (d) makes things spin
32. 32.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
33. 33.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 680 Ω resistor? (a) blue-grey-black (b) blue-grey-red (c) blue-grey-brown (d) grey-blue-brown
34. 34.💡 A red LED uses 2 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
35. 35.🧮 Resistors of 470 Ω, 10 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
36. 36.True or false: to set the AC to 24 °C wastes electricity. (a) False (b) True
37. 37.🔍 Which is the odd one out? (a) use daylight to read (b) close the fridge quickly (c) switch off empty rooms (d) use old filament bulbs
38. 38.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?

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