Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 274 · 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 0.4 V battery is joined to 2 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
2. 2.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
3. 3.🧩 Which component boosts a small signal? (a) diode (b) LDR (c) transistor (d) buzzer
4. 4.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
5. 5.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
6. 6.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
7. 7.🧮 A 3 V battery is joined to 12 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
8. 8.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
9. 9.What does a transistor do? (a) boosts a small signal (b) is a resistance knob (c) has coloured bands (d) limits the current
10. 10.⚡ A 24 W device works on 24 V. What current does it take (in amperes)? =
11. 11.🧩 Which component senses how hot it is? (a) diode (b) thermistor (c) resistor (d) capacitor
12. 12.🧩 Which component makes a beeping sound? (a) buzzer (b) resistor (c) LDR (d) motor
13. 13.True or false: to run fans in empty rooms saves electricity. (a) True (b) False
14. 14.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
16. 16.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
17. 17.What does a fuse do? (a) lets current go one way (b) limits the current (c) blows if current is high (d) is a resistance knob
18. 18.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
21. 21.📏 Which unit measures the push of a cell? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
22. 22.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🧩 Which component stores a little charge? (a) capacitor (b) transistor (c) resistor (d) buzzer
25. 25.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 71 Ω resistor? (a) brown-violet-black (b) violet-brown-brown (c) grey-brown-black (d) violet-brown-black
26. 26.Which of these is measured in ohms (Ω)? (a) energy used each second (b) power (c) the push of a cell (d) resistance
27. 27.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
28. 28.True or false: to leave fridge door open saves electricity. (a) True (b) False
29. 29.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V ÷ R (c) I = R ÷ V (d) I = V × R
30. 30.🔺 A 1.2 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
31. 31.🧩 Which component lets current go one way? (a) diode (b) capacitor (c) LDR (d) potentiometer
32. 32.📏 How many kilowatts (kW) is 1850 W? =
33. 33.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
34. 34.🧮 A 1.8 V battery is joined to 3 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
35. 35.🧮 Resistors of 150 Ω, 20 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
36. 36.🌈 A resistor has the colour bands grey, yellow, red. What is its value in kilo-ohms (kΩ)? =
37. 37.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
38. 38.🌈 A resistor has the colour bands orange, orange, orange. What is its value (in ohms)?
39. 39.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it makes a sound (d) it does not light
40. 40.🧮 Resistors of 50 Ω, 50 Ω, 47 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?

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