Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 939 · 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.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
2. 2.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
3. 3.🌈 A resistor has the colour bands grey, blue, red. What is its value (in ohms)?
4. 4.🧾 A 100 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
5. 5.🔺 A current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
6. 6.True or false: resistance is measured in ohms (Ω). (a) True (b) False
7. 7.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) less than either one (d) more than either one
8. 8.True or false: current is measured in ohms (Ω). (a) True (b) False
9. 9.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.⚡ A 7.5 W device works on 5 V. What current does it take (in amperes)? =
11. 11.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
12. 12.What does an LED do? (a) beeps for an alarm (b) limits the current (c) blows if current is high (d) glows using little power
13. 13.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
14. 14.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
15. 15.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
16. 16.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
17. 17.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a motor (d) a resistor
18. 18.True or false: a thermistor senses how hot it is. (a) False (b) True
19. 19.🧩 Which component stores a little charge? (a) LED (b) buzzer (c) transistor (d) capacitor
20. 20.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
21. 21.🧩 Which component boosts a small signal? (a) capacitor (b) LED (c) transistor (d) potentiometer
22. 22.🧮 Resistors of 10 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
23. 23.🔺 A current of 2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
24. 24.Which of these is measured in watts (W)? (a) energy used each second (b) voltage (c) the push of a cell (d) resistance
25. 25.🌈 A resistor has the colour bands red, orange, black. What is its value (in ohms)?
26. 26.True or false: a potentiometer beeps for an alarm. (a) False (b) True
27. 27.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) the one nearest an end (d) any band
28. 28.🔺 A current of 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🧾 A family uses 30 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
30. 30.What does a capacitor do? (a) turns a fan or wheels (b) stores a little charge (c) beeps for an alarm (d) makes things spin
31. 31.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
32. 32.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the flow of water (d) the pipe colour
33. 33.🔺 A current of 3 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
34. 34.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
35. 35.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
36. 36.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
37. 37.🧩 Which part changes electrical energy into sound? (a) a diode (b) a resistor (c) a buzzer (d) a capacitor
38. 38.🌈 In the resistor colour code, which number does brown stand for?
39. 39.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V × R (d) I = V ÷ R
40. 40.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =

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