Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 230 · 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 unit measures energy used each second? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
2. 2.Which of these saves electricity? (a) use old filament bulbs (b) leave fridge door open (c) leave the TV on standby (d) close the fridge quickly
3. 3.🧮 A 2.5 V battery is joined to 6 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
4. 4.🧩 Which component boosts a small signal? (a) diode (b) transistor (c) thermistor (d) resistor
5. 5.🌈 A resistor has the colour bands orange, red, brown. What is its value (in ohms)?
6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 50 % (d) 0 %
7. 7.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
8. 8.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
9. 9.Which of these is measured in ohms (Ω)? (a) voltage (b) how much a part resists (c) energy used each second (d) the push of a cell
10. 10.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
11. 11.What does an LED do? (a) has coloured bands (b) makes things spin (c) smooths a wobbly supply (d) glows using little power
12. 12.📏 How many kilo-ohms (kΩ) is 4700 Ω? =
13. 13.🌈 Which band is read first on a resistor? (a) the gold band (b) any band (c) the one nearest an end (d) the widest gap
14. 14.🧮 A 150 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
15. 15.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
16. 16.True or false: to use old filament bulbs saves electricity. (a) False (b) True
17. 17.🌈 A resistor has the colour bands orange, black, orange. What is its value in kilo-ohms (kΩ)? =
18. 18.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
19. 19.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
20. 20.📏 Which unit measures voltage? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
21. 21.Which of these saves electricity? (a) run fans in empty rooms (b) leave the TV on standby (c) use daylight to read (d) use old filament bulbs
22. 22.🧮 A 330 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)?
23. 23.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.🧩 Which component is a resistance knob? (a) capacitor (b) potentiometer (c) diode (d) thermistor
25. 25.💡 An LED is joined to a 5 V battery with no 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
26. 26.🌈 In the resistor colour code, which number does brown stand for?
27. 27.🧩 Which component stores a little charge? (a) transistor (b) buzzer (c) fuse (d) capacitor
28. 28.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
29. 29.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
30. 30.🧮 A 3.5 V battery is joined to 2 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
31. 31.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
32. 32.📏 How many ohms (Ω) is 2.4 kΩ?
33. 33.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets smaller (d) gets bigger
34. 34.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.🔺 A current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
37. 37.True or false: a buzzer has coloured bands. (a) False (b) True
38. 38.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
39. 39.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
40. 40.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =

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