Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 400 · 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.True or false: to leave fridge door open wastes electricity. (a) False (b) True
2. 2.📏 How many ohms (Ω) is 1.3 kΩ?
3. 3.True or false: the voltmeter is joined in series. (a) False (b) True
4. 4.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) measure heat (d) spin a wheel
5. 5.💡 An LED is joined to a 6 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
6. 6.🌈 In the resistor colour code, which number does brown stand for?
7. 7.🧩 Which component makes a beeping sound? (a) diode (b) motor (c) buzzer (d) LED
8. 8.🔺 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
9. 9.🧾 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
10. 10.🌈 A resistor has the colour bands brown, blue, red. What is its value in kilo-ohms (kΩ)? =
11. 11.🌈 In the resistor colour code, which number does grey stand for?
12. 12.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) less than either one (d) more than either one
13. 13.🧾 A family uses 170 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
14. 14.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🌈 A resistor has the colour bands grey, green, black. What is its value (in ohms)?
16. 16.What does a capacitor do? (a) lets current go one way (b) stores a little charge (c) makes a beeping sound (d) limits the current
17. 17.🧮 A 33 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
18. 18.🧮 A 0.8 V battery is joined to 6 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
19. 19.📏 How many kilowatts (kW) is 4950 W? =
20. 20.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) zero (d) stay the same
21. 21.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it does not light (c) it changes colour (d) it makes a sound
22. 22.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
23. 23.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 watt
25. 25.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to store charge (d) to limit the current
26. 26.🔺 A 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
27. 27.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
28. 28.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
29. 29.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 25 % (d) 0 %
30. 30.🔺 A current of 2.5 A flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a motor (d) a resistor
32. 32.🔺 A 2 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
33. 33.Which of these wastes electricity? (a) switch off empty rooms (b) close the fridge quickly (c) iron one shirt at a time (d) set the AC to 24 °C
34. 34.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) the push of a cell (c) resistance (d) power
35. 35.🔺 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
36. 36.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
37. 37.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
39. 39.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
40. 40.🌈 A resistor has the colour bands brown, brown, red. What is its value (in ohms)?

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