Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 473 · 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.🔺 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
2. 2.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
3. 3.True or false: the ammeter measures current. (a) True (b) False
4. 4.🧮 Resistors of 68 Ω, 20 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.What does an LED do? (a) senses how hot it is (b) glows using little power (c) smooths a wobbly supply (d) lets current go one way
6. 6.📏 How many kilo-ohms (kΩ) is 7000 Ω? =
7. 7.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
8. 8.True or false: a transistor turns a fan or wheels. (a) True (b) False
9. 9.🧮 A 2.4 V battery is joined to 6 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
10. 10.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = I ÷ V (c) R = V + I (d) R = V × I
11. 11.🔺 A 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
12. 12.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
13. 13.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
14. 14.True or false: the voltmeter is joined in series. (a) False (b) True
15. 15.💡 An LED is joined to a 5 V battery through a 330 Ω 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
16. 16.🌈 A resistor has the colour bands green, orange, black. What is its value (in ohms)?
17. 17.🌈 A resistor has the colour bands orange, yellow, red. What is its value (in ohms)?
18. 18.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.🔺 A 10 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
20. 20.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
21. 21.📏 Which unit measures resistance? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
22. 22.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
23. 23.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 100 (c) 10 (d) 1024
24. 24.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) less than either one (d) always zero
25. 25.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
26. 26.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an oil lamp (c) an LED lamp (d) a candle
27. 27.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
28. 28.True or false: the ammeter is joined across a part. (a) False (b) True
29. 29.🧮 A 14 V battery is joined to 10 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
30. 30.True or false: an LDR stores a little charge. (a) True (b) False
31. 31.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧩 Which component glows using little power? (a) buzzer (b) resistor (c) LED (d) thermistor
33. 33.📏 Which unit measures the flow of charge? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
34. 34.🌈 In the resistor colour code, which number does violet stand for?
35. 35.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
36. 36.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
37. 37.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a fuse (d) a resistor
38. 38.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
39. 39.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) the size of a cell (d) energy used each second
40. 40.True or false: an LED glows using little power. (a) False (b) True

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