Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 479 · 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.🧮 Resistors of 20 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
2. 2.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
3. 3.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
4. 4.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a bigger tank (c) the water pressure (d) a narrow pipe
5. 5.🌈 In the resistor colour code, which number does red stand for?
6. 6.True or false: to leave fridge door open wastes electricity. (a) False (b) True
7. 7.🧩 Which component turns a fan or wheels? (a) diode (b) LDR (c) motor (d) potentiometer
8. 8.🧩 Which component stores a little charge? (a) LED (b) resistor (c) capacitor (d) motor
9. 9.🌈 In the resistor colour code, which number does green stand for?
10. 10.💡 What happens if an LED is put in backwards? (a) it does not light (b) it makes a sound (c) it changes colour (d) it lights brighter
11. 11.Which of these is measured in amperes (A)? (a) resistance (b) how much a part resists (c) voltage (d) current
12. 12.Which of these saves electricity? (a) iron one shirt at a time (b) use old filament bulbs (c) run fans in empty rooms (d) use daylight to read
13. 13.💡 An LED is joined to a 6 V battery through a 470 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) does not light (b) may burn out (c) lights up
14. 14.🧮 A 150 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)?
15. 15.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
16. 16.True or false: to leave fridge door open saves electricity. (a) True (b) False
17. 17.Which of these is measured in watts (W)? (a) the push of a cell (b) how much a part resists (c) current (d) power
18. 18.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) an oil lamp (d) a filament bulb
19. 19.What does a potentiometer do? (a) is a resistance knob (b) smooths a wobbly supply (c) limits the current (d) stores a little charge
20. 20.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1000 (d) 1024
21. 21.Which of these is measured in volts (V)? (a) energy used each second (b) power (c) current (d) the push of a cell
22. 22.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔍 Which is the odd one out? (a) close the fridge quickly (b) use daylight to read (c) iron one shirt at a time (d) use LED lamps
24. 24.True or false: to set the AC to 24 °C saves electricity. (a) True (b) False
25. 25.What does a thermistor do? (a) lets current go one way (b) senses how hot it is (c) glows using little power (d) smooths a wobbly supply
26. 26.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔺 A 3 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
28. 28.🔍 Which is the odd one out? (a) run fans in empty rooms (b) iron one shirt at a time (c) leave fridge door open (d) unplug idle chargers
29. 29.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets smaller (d) gets bigger
30. 30.Which of these wastes electricity? (a) use daylight to read (b) set the AC to 24 °C (c) iron one shirt at a time (d) use LED lamps
31. 31.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
32. 32.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = V + I (d) R = I ÷ V
33. 33.True or false: the ammeter is joined in series. (a) False (b) True
34. 34.🧾 A family uses 140 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
35. 35.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
36. 36.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
37. 37.🔍 Which is the odd one out? (a) leave fridge door open (b) use LED lamps (c) leave the TV on standby (d) run fans in empty rooms
38. 38.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
39. 39.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
40. 40.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?

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