Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 505 · 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 band is read first on a resistor? (a) any band (b) the one nearest an end (c) the widest gap (d) the gold band
2. 2.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
3. 3.What does a potentiometer do? (a) lets current go one way (b) glows using little power (c) is a resistance knob (d) has coloured bands
4. 4.📏 How many ohms (Ω) is 0.4 kΩ?
5. 5.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 98000 Ω resistor? (a) white-grey-red (b) grey-white-orange (c) white-grey-orange (d) white-grey-yellow
6. 6.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
7. 7.🔺 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
8. 8.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🌈 A resistor has the colour bands red, brown, orange. What is its value in kilo-ohms (kΩ)? =
10. 10.🌈 A resistor has the colour bands violet, red, orange. What is its value (in ohms)?
11. 11.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
12. 12.🧮 A 10 V battery is joined to 4 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
13. 13.True or false: an LDR blows if current is high. (a) True (b) False
14. 14.⚡ A 7.5 W device works on 5 V. What current does it take (in amperes)? =
15. 15.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
16. 16.🧾 A 2000 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
17. 17.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a motor (d) a resistor
18. 18.🧮 A 100 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
19. 19.True or false: an LDR senses how bright it is. (a) True (b) False
20. 20.🌈 A resistor has the colour bands orange, black, black. What is its value (in ohms)?
21. 21.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) the push of a cell (c) power (d) how much a part resists
22. 22.True or false: a potentiometer senses how hot it is. (a) True (b) False
23. 23.🌈 A resistor has the colour bands brown, violet, brown. What is its value (in ohms)?
24. 24.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to make it brighter (c) to limit the current (d) to store charge
25. 25.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🧩 A capacitor in a circuit can … (a) spin a wheel (b) measure heat (c) store charge briefly (d) make light
27. 27.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 4.25 V supply. What current flows (in mA)?
28. 28.True or false: a diode lets current go one way. (a) True (b) False
29. 29.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
30. 30.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🔍 Which is the odd one out? (a) iron one shirt at a time (b) leave fridge door open (c) unplug idle chargers (d) leave the TV on standby
32. 32.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) zero (d) stay the same
33. 33.🧮 A 2.5 V battery is joined to 6 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
34. 34.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🌈 A resistor has the colour bands brown, brown, red. What is its value in kilo-ohms (kΩ)? =
36. 36.🧩 Which component blows if current is high? (a) capacitor (b) buzzer (c) fuse (d) motor
37. 37.Which of these is measured in watts (W)? (a) current (b) how much a part resists (c) power (d) resistance
38. 38.🔺 A current of 0.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.True or false: the ammeter is joined in series. (a) True (b) False
40. 40.Which of these saves electricity? (a) run fans in empty rooms (b) leave fridge door open (c) leave the TV on standby (d) close the fridge quickly

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