Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 512 · 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 I? (a) I = V ÷ R (b) I = V × R (c) I = V + R (d) I = R ÷ V
2. 2.🌈 In the resistor colour code, which number does blue stand for?
3. 3.📏 How many milliamperes (mA) is 0.85 A?
4. 4.🔺 A 4.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
5. 5.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
6. 6.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🔺 A current of 2 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
8. 8.📏 How many kilowatts (kW) is 1600 W? =
9. 9.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 25 % (d) 0 %
11. 11.🔺 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
12. 12.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
13. 13.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to make it brighter (c) to store charge (d) to change its colour
14. 14.🌈 In the resistor colour code, which number does red stand for?
15. 15.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
16. 16.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
17. 17.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a buzzer (d) a capacitor
18. 18.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🌈 A resistor has the colour bands grey, yellow, orange. What is its value (in ohms)?
20. 20.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave fridge door open (c) unplug idle chargers (d) run fans in empty rooms
21. 21.What does an LED do? (a) has coloured bands (b) senses how hot it is (c) glows using little power (d) lets current go one way
22. 22.True or false: the push of a cell is measured in volts (V). (a) False (b) True
23. 23.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
25. 25.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
26. 26.🧩 Which component boosts a small signal? (a) transistor (b) capacitor (c) thermistor (d) potentiometer
27. 27.Which of these is measured in amperes (A)? (a) voltage (b) energy used each second (c) current (d) the push of a cell
28. 28.🧮 Resistors of 68 Ω, 20 Ω, 220 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
29. 29.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
30. 30.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it changes colour (d) it does not light
31. 31.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
32. 32.True or false: a buzzer lets current go one way. (a) True (b) False
33. 33.🧾 A family uses 100 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
34. 34.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
35. 35.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
36. 36.💡 An LED is joined to a 5 V battery through a 1000 Ω 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
37. 37.What does a resistor do? (a) is a resistance knob (b) has coloured bands (c) beeps for an alarm (d) smooths a wobbly supply
38. 38.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
39. 39.True or false: a capacitor stores a little charge. (a) True (b) False
40. 40.🔺 A current of 0.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?

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