Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 355 · 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.Which of these is measured in watts (W)? (a) current (b) the flow of charge (c) voltage (d) energy used each second
2. 2.📏 How many ohms (Ω) is 2.2 kΩ?
3. 3.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
4. 4.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it does not light (d) it makes a sound
5. 5.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) becomes zero (d) gets bigger
7. 7.🔺 A 10 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
8. 8.🔺 A current of 2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
9. 9.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
10. 10.Which of these is measured in amperes (A)? (a) energy used each second (b) how much a part resists (c) the flow of charge (d) resistance
11. 11.🌈 A resistor has the colour bands blue, brown, orange. What is its value in kilo-ohms (kΩ)? =
12. 12.🧩 Which component makes things spin? (a) fuse (b) buzzer (c) transistor (d) motor
13. 13.Which of these wastes electricity? (a) switch off empty rooms (b) use daylight to read (c) run fans in empty rooms (d) close the fridge quickly
14. 14.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
15. 15.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
16. 16.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
17. 17.🧩 Which component boosts a small signal? (a) diode (b) motor (c) transistor (d) buzzer
18. 18.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
19. 19.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🧩 Which component senses how hot it is? (a) thermistor (b) diode (c) fuse (d) LDR
21. 21.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) an oil lamp (d) a candle
22. 22.🔺 A current of 2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🔺 A current of 40 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
25. 25.🌈 In the resistor colour code, which number does black stand for?
26. 26.True or false: a resistor limits the current. (a) True (b) False
27. 27.🌈 A resistor has the colour bands blue, violet, red. What is its value (in ohms)?
28. 28.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🧩 Which part changes electrical energy into movement? (a) a motor (b) a resistor (c) a fuse (d) an LED
30. 30.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
31. 31.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
32. 32.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
33. 33.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
34. 34.⚡ A device works on 1.5 V and takes 0.5 A. What is its power (in watts)? =
35. 35.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.📏 Which unit measures current? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
37. 37.🧩 Which component has coloured bands? (a) LDR (b) resistor (c) potentiometer (d) capacitor
38. 38.🧮 Resistors of 470 Ω, 100 Ω, 330 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
39. 39.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
40. 40.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the pipe colour (c) a narrow pipe (d) the flow of water

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