Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 303 · 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 device works on 24 V and takes 0.5 A. What is its power (in watts)? =
2. 2.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) store charge briefly (d) measure heat
3. 3.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
4. 4.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
5. 5.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water tank lid (c) the pipe colour (d) the water pressure
6. 6.🧮 Resistors of 22 Ω, 10 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
7. 7.🔺 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
8. 8.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
9. 9.📏 How many kilo-ohms (kΩ) is 5300 Ω? =
10. 10.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
11. 11.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
12. 12.🧾 A family uses 120 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
13. 13.⚡ A 1.2 W device works on 6 V. What current does it take (in amperes)? =
14. 14.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 50 % (d) 5 %
15. 15.True or false: the flow of charge is measured in amperes (A). (a) True (b) False
16. 16.🧮 A 3 V battery is joined to 3 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
17. 17.📏 Which unit measures voltage? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
18. 18.📏 Which unit measures resistance? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
19. 19.📏 How many ohms (Ω) is 4.2 kΩ?
20. 20.💡 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
21. 21.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) an LED lamp (d) a filament bulb
22. 22.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
25. 25.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
26. 26.🔺 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
27. 27.🔺 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
28. 28.💡 An LED is joined to a 9 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) does not light (c) may burn out
29. 29.🧾 A family uses 180 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
30. 30.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) less than either one (d) their sum
31. 31.🧩 Which component lets current go one way? (a) thermistor (b) capacitor (c) diode (d) motor
32. 32.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
33. 33.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
34. 34.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🧮 An 8 V battery is joined to 10 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
36. 36.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
37. 37.📏 How many milliamperes (mA) is 2.12 A?
38. 38.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
39. 39.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
40. 40.🔺 A current of 50 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?

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