Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 106 · 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.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
2. 2.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the flow of water (c) the pipe colour (d) a narrow pipe
3. 3.🔺 A current of 0.25 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) any band (d) the one nearest an end
5. 5.True or false: the voltmeter measures voltage. (a) True (b) False
6. 6.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
7. 7.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 50 % (d) 5 %
8. 8.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = I ÷ V (d) P = V ÷ I
9. 9.🔺 A 6 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
10. 10.📏 How many milliamperes (mA) is 2.6 A?
11. 11.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
12. 12.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a motor (d) a fuse
13. 13.🔺 A 10 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
14. 14.🌈 In the resistor colour code, which number does yellow stand for?
15. 15.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = V ÷ R (d) I = R ÷ V
17. 17.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) make light (d) measure heat
18. 18.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
19. 19.True or false: a buzzer makes a beeping sound. (a) True (b) False
20. 20.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
21. 21.True or false: a resistor has coloured bands. (a) False (b) True
22. 22.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🌈 A resistor has the colour bands orange, black, yellow. What is its value in kilo-ohms (kΩ)? =
24. 24.💡 What happens if an LED is put in backwards? (a) it does not light (b) it lights brighter (c) it makes a sound (d) it changes colour
25. 25.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
26. 26.🔍 Which is the odd one out? (a) leave fridge door open (b) switch off empty rooms (c) run fans in empty rooms (d) leave the TV on standby
27. 27.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
28. 28.True or false: the ammeter is joined in series. (a) True (b) False
29. 29.🌈 A resistor has the colour bands violet, violet, orange. What is its value (in ohms)?
30. 30.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 100 (c) 10 (d) 1024
31. 31.🌈 A resistor has the colour bands red, blue, brown. What is its value (in ohms)?
32. 32.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
33. 33.🧩 Which component smooths a wobbly supply? (a) capacitor (b) thermistor (c) buzzer (d) resistor
34. 34.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
35. 35.True or false: a transistor boosts a small signal. (a) False (b) True
36. 36.🔺 A 50 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
37. 37.🔺 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
38. 38.🔺 A current of 50 mA flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.🧩 Which component senses how hot it is? (a) motor (b) LDR (c) thermistor (d) transistor
40. 40.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one

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