Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 997 · 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 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
2. 2.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
3. 3.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
4. 4.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water pressure (c) the tap handle (d) the water tank lid
5. 5.💡 An LED is joined to a 12 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
6. 6.📏 How many watts (W) is 2.9 kW?
7. 7.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) gets bigger (d) becomes zero
8. 8.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
10. 10.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
11. 11.🌈 A resistor has the colour bands white, grey, black. What is its value (in ohms)?
12. 12.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) less than either one (d) their sum
13. 13.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
14. 14.🌈 A resistor has the colour bands violet, orange, orange. What is its value in kilo-ohms (kΩ)? =
15. 15.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) large electric dial (d) low energy device
16. 16.🧮 A 330 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
17. 17.📏 How many kilowatts (kW) is 3100 W? =
18. 18.🌈 In the resistor colour code, which number does yellow stand for?
19. 19.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
21. 21.📏 How many milliamperes (mA) is 0.76 A?
22. 22.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a resistor (d) a fuse
23. 23.Which of these is measured in amperes (A)? (a) the push of a cell (b) current (c) voltage (d) how much a part resists
24. 24.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
25. 25.True or false: the voltmeter is joined across a part. (a) False (b) True
26. 26.Which of these is measured in watts (W)? (a) voltage (b) power (c) the push of a cell (d) resistance
27. 27.True or false: a thermistor senses how hot it is. (a) False (b) True
28. 28.🧾 A family uses 180 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
29. 29.🔍 Which is the odd one out? (a) close the fridge quickly (b) use daylight to read (c) use LED lamps (d) use old filament bulbs
30. 30.📏 How many watts (W) is 0.6 kW?
31. 31.💡 What happens if an LED is put in backwards? (a) it does not light (b) it lights brighter (c) it changes colour (d) it makes a sound
32. 32.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 210 Ω resistor? (a) red-brown-black (b) red-brown-brown (c) red-brown-red (d) brown-red-brown
33. 33.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
34. 34.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
35. 35.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) make light (d) store charge briefly
36. 36.📏 Which unit measures how much a part resists? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
37. 37.📏 How many amperes (A) is 850 mA? =
38. 38.🧾 A family uses 30 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
39. 39.⚡ A 4.5 W device works on 9 V. What current does it take (in amperes)? =
40. 40.📏 Which unit measures voltage? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)

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