Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 243 · 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.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
2. 2.📏 Which unit measures resistance? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
3. 3.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
4. 4.🧮 A 5.5 V battery is joined to 10 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
5. 5.🧾 A family uses 120 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
6. 6.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = I ÷ V (c) R = V + I (d) R = V × I
8. 8.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
9. 9.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
10. 10.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
11. 11.True or false: the voltmeter is joined across a part. (a) False (b) True
12. 12.True or false: a fuse blows if current is high. (a) False (b) True
13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
14. 14.📏 How many kilowatts (kW) is 1600 W? =
15. 15.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
16. 16.🧩 Which component is a resistance knob? (a) potentiometer (b) fuse (c) LDR (d) diode
17. 17.True or false: the ammeter is joined across a part. (a) True (b) False
18. 18.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
19. 19.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
20. 20.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
21. 21.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
22. 22.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a diode (d) a resistor
23. 23.🌈 A resistor has the colour bands blue, red, brown. What is its value (in ohms)?
24. 24.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
25. 25.🧮 A 20 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)?
26. 26.🧮 Resistors of 470 Ω, 47 Ω, 150 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
27. 27.📏 How many kilowatts (kW) is 3350 W? =
28. 28.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to limit the current (d) to make it brighter
29. 29.📏 How many milliamperes (mA) is 2.22 A?
30. 30.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
31. 31.🧾 A 2000 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
32. 32.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the gold band (d) the one nearest an end
33. 33.🌈 A resistor has the colour bands yellow, red, yellow. What is its value in kilo-ohms (kΩ)? =
34. 34.💡 A red LED uses 2 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
35. 35.🔺 A current of 40 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
36. 36.Which of these is measured in ohms (Ω)? (a) voltage (b) power (c) current (d) resistance
37. 37.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
38. 38.True or false: an LDR senses how bright it is. (a) False (b) True
39. 39.🔺 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
40. 40.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?

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