Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 249 · 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 500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
2. 2.What does a motor do? (a) has coloured bands (b) stores a little charge (c) boosts a small signal (d) turns a fan or wheels
3. 3.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🌈 A resistor has the colour bands grey, orange, red. What is its value in kilo-ohms (kΩ)? =
5. 5.Which of these is measured in amperes (A)? (a) resistance (b) the flow of charge (c) energy used each second (d) power
6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 0 % (d) 50 %
7. 7.📏 How many kilo-ohms (kΩ) is 1600 Ω? =
8. 8.🧮 A 50 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
9. 9.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
10. 10.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
11. 11.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) measure heat (d) make light
12. 12.🧮 Resistors of 22 Ω, 100 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
13. 13.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to make it brighter (d) to change its colour
14. 14.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) energy used each second (d) the colour of light
15. 15.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
16. 16.🔺 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
17. 17.📏 Which unit measures current? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
18. 18.True or false: the ammeter is joined in series. (a) False (b) True
19. 19.🧮 A 3 V battery is joined to 12 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
20. 20.📏 How many milliamperes (mA) is 2.48 A?
21. 21.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the one nearest an end (d) the widest gap
22. 22.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
23. 23.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V × R (d) I = V + R
24. 24.🧩 Which component stores a little charge? (a) capacitor (b) potentiometer (c) LDR (d) thermistor
25. 25.🔺 A current of 3 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🔺 An 18 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
27. 27.🔺 A 9 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
28. 28.💡 A red LED uses 2 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
29. 29.Which of these is measured in watts (W)? (a) current (b) power (c) the push of a cell (d) resistance
30. 30.True or false: the ammeter measures voltage. (a) True (b) False
31. 31.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
32. 32.What does an LED do? (a) stores a little charge (b) makes a beeping sound (c) senses how hot it is (d) glows using little power
33. 33.🔺 A current of 25 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
35. 35.True or false: to close the fridge quickly saves electricity. (a) False (b) True
36. 36.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
37. 37.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
38. 38.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
39. 39.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) light-emitting diode (d) low energy device
40. 40.🌈 A resistor has the colour bands white, white, brown. What is its value (in ohms)?

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