Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 886 · 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.🔍 Which is the odd one out? (a) leave the TV on standby (b) set the AC to 24 °C (c) leave fridge door open (d) use old filament bulbs
2. 2.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
3. 3.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
4. 4.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to make it brighter (d) to limit the current
5. 5.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
6. 6.🌈 In the resistor colour code, which number does white stand for?
7. 7.🧮 A 10 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
8. 8.🌈 A resistor has the colour bands violet, blue, red. What is its value (in ohms)?
9. 9.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
10. 10.True or false: the ammeter is joined in series. (a) False (b) True
11. 11.🔍 Which is the odd one out? (a) iron one shirt at a time (b) use LED lamps (c) leave the TV on standby (d) run fans in empty rooms
12. 12.🧾 A family uses 150 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
13. 13.🔺 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
14. 14.Which of these is measured in watts (W)? (a) resistance (b) how much a part resists (c) the push of a cell (d) power
15. 15.💡 An LED is joined to a 9 V battery through a 1000 Ω 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
16. 16.🧩 Which component is a resistance knob? (a) thermistor (b) potentiometer (c) resistor (d) LDR
17. 17.Which of these wastes electricity? (a) close the fridge quickly (b) use old filament bulbs (c) use daylight to read (d) switch off empty rooms
18. 18.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
19. 19.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = V + I (d) P = I ÷ V
20. 20.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
21. 21.🧩 Which component has coloured bands? (a) resistor (b) transistor (c) motor (d) LDR
22. 22.🧾 A 200 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
23. 23.Which of these saves electricity? (a) use old filament bulbs (b) use daylight to read (c) leave the TV on standby (d) leave fridge door open
24. 24.What does a motor do? (a) stores a little charge (b) turns a fan or wheels (c) senses how hot it is (d) boosts a small signal
25. 25.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
26. 26.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
27. 27.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 25 % (d) 0 %
28. 28.Which of these is measured in amperes (A)? (a) the push of a cell (b) power (c) how much a part resists (d) the flow of charge
29. 29.🧩 Which component makes things spin? (a) fuse (b) thermistor (c) capacitor (d) motor
30. 30.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
31. 31.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
32. 32.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🌈 A resistor has the colour bands violet, grey, black. What is its value (in ohms)?
35. 35.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
36. 36.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
37. 37.True or false: a resistor makes a beeping sound. (a) False (b) True
38. 38.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) store charge briefly (d) measure heat
39. 39.🌈 A resistor has the colour bands brown, blue, orange. What is its value in kilo-ohms (kΩ)? =
40. 40.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same

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