Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 23 · 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 20 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
2. 2.Which of these is measured in watts (W)? (a) current (b) the flow of charge (c) voltage (d) energy used each second
3. 3.What does a thermistor do? (a) stores a little charge (b) beeps for an alarm (c) senses how hot it is (d) turns a fan or wheels
4. 4.What does a capacitor do? (a) smooths a wobbly supply (b) senses how bright it is (c) lets current go one way (d) is a resistance knob
5. 5.🌈 In the resistor colour code, which number does red stand for?
6. 6.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) spin a wheel (d) measure heat
7. 7.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
8. 8.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
9. 9.What does a diode do? (a) lets current go one way (b) smooths a wobbly supply (c) senses how bright it is (d) limits the current
10. 10.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 50 % (d) 25 %
11. 11.What does a motor do? (a) is a resistance knob (b) lets current go one way (c) makes things spin (d) makes a beeping sound
12. 12.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.🧮 A 2 V battery is joined to 2 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
14. 14.🧮 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)?
15. 15.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = I ÷ V (d) P = V + I
16. 16.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🧮 Resistors of 150 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
18. 18.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
19. 19.🌈 A resistor has the colour bands violet, orange, brown. What is its value (in ohms)?
20. 20.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
21. 21.🌈 A resistor has the colour bands blue, grey, orange. What is its value in kilo-ohms (kΩ)? =
22. 22.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 60 (c) 10 (d) 100
23. 23.🌈 A resistor has the colour bands white, brown, red. What is its value (in ohms)?
24. 24.🧩 Which component boosts a small signal? (a) diode (b) potentiometer (c) thermistor (d) transistor
25. 25.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🔺 A current of 2.5 A flows when 37.5 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.📏 How many amperes (A) is 20 mA? =
28. 28.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = I ÷ V (d) R = V + I
29. 29.Which of these is measured in watts (W)? (a) power (b) current (c) how much a part resists (d) resistance
30. 30.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
31. 31.True or false: an LDR is a resistance knob. (a) True (b) False
32. 32.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
33. 33.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
34. 34.🧾 A family uses 170 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
35. 35.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🧩 Which component limits the current? (a) resistor (b) motor (c) LED (d) transistor
38. 38.⚡ A 3 W device works on 3 V. What current does it take (in amperes)? =
39. 39.What does a fuse do? (a) stores a little charge (b) beeps for an alarm (c) blows if current is high (d) limits the current
40. 40.🔍 Which is the odd one out? (a) use old filament bulbs (b) close the fridge quickly (c) run fans in empty rooms (d) leave the TV on standby

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