Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 8 · 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 1.4 V battery is joined to 12 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
2. 2.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) measure heat (d) spin a wheel
3. 3.🧩 Which component is a resistance knob? (a) buzzer (b) thermistor (c) potentiometer (d) motor
4. 4.🌈 In the resistor colour code, which number does grey stand for?
5. 5.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
6. 6.📏 Which unit measures power? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
7. 7.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
8. 8.🧩 Which component turns a fan or wheels? (a) LDR (b) resistor (c) LED (d) motor
9. 9.Which of these saves electricity? (a) use old filament bulbs (b) run fans in empty rooms (c) use daylight to read (d) leave fridge door open
10. 10.🔺 A current of 1.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🌈 A resistor has the colour bands yellow, black, red. What is its value in kilo-ohms (kΩ)? =
12. 12.What does a capacitor do? (a) beeps for an alarm (b) senses how bright it is (c) senses how hot it is (d) stores a little charge
13. 13.True or false: power is measured in volts (V). (a) False (b) True
14. 14.🌈 A resistor has the colour bands green, orange, red. What is its value in kilo-ohms (kΩ)? =
15. 15.🧾 A 50 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
16. 16.🌈 In the resistor colour code, which number does blue stand for?
17. 17.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
19. 19.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
20. 20.True or false: a diode limits the current. (a) True (b) False
21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 37000 Ω resistor? (a) orange-violet-yellow (b) orange-violet-red (c) orange-violet-orange (d) violet-orange-orange
22. 22.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
23. 23.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
24. 24.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
25. 25.True or false: a resistor senses how bright it is. (a) True (b) False
26. 26.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
27. 27.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
28. 28.🔺 A 30 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
29. 29.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) energy used each second (d) the length of a wire
30. 30.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
31. 31.🧮 A 220 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
32. 32.True or false: voltage is measured in volts (V). (a) True (b) False
33. 33.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
34. 34.🔺 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
35. 35.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the widest gap (d) the one nearest an end
36. 36.⚡ A 12 W device works on 12 V. What current does it take (in amperes)? =
37. 37.🧾 A family uses 120 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
38. 38.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
39. 39.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
40. 40.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the flow of water (c) the pipe colour (d) the water pressure

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