Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 681 · 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: a capacitor smooths a wobbly supply. (a) True (b) False
2. 2.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
3. 3.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
4. 4.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to limit the current (d) to make it brighter
5. 5.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = I × R (d) V = R ÷ I
6. 6.🧾 A 50 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
7. 7.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
8. 8.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
9. 9.🔺 A current of 0.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🧮 A 22 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)?
11. 11.🌈 A resistor has the colour bands brown, green, red. What is its value in kilo-ohms (kΩ)? =
12. 12.🧩 Which component makes things spin? (a) transistor (b) motor (c) LDR (d) potentiometer
13. 13.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
14. 14.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
15. 15.True or false: a diode limits the current. (a) True (b) False
16. 16.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
17. 17.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
18. 18.📏 Which unit measures how much a part resists? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
19. 19.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) smaller (d) stay the same
20. 20.🧮 A 220 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
21. 21.True or false: a potentiometer is a resistance knob. (a) False (b) True
22. 22.⚡ 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
23. 23.🔺 A current of 2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
24. 24.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
25. 25.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
26. 26.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
27. 27.⚡ A 1.5 W device works on 1.5 V. What current does it take (in amperes)? =
28. 28.🧮 Resistors of 330 Ω, 47 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
29. 29.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7800 Ω resistor? (a) violet-grey-red (b) grey-violet-red (c) violet-grey-orange (d) violet-grey-brown
32. 32.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V ÷ R (d) I = V + R
33. 33.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap
34. 34.🌈 A resistor has the colour bands brown, white, brown. What is its value (in ohms)?
35. 35.🌈 In the resistor colour code, which number does yellow stand for?
36. 36.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
37. 37.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🧮 A 7 V battery is joined to 8 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
39. 39.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
40. 40.🧾 A family uses 170 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?

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