Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 348 · 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.True or false: to switch off empty rooms saves electricity. (a) True (b) False
2. 2.🔺 A current of 2 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
3. 3.⚡ A 1.2 W device works on 6 V. What current does it take (in amperes)? =
4. 4.True or false: to run fans in empty rooms wastes electricity. (a) False (b) True
5. 5.🔺 An 8.25 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
6. 6.True or false: a capacitor stores a little charge. (a) True (b) False
7. 7.🧮 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)?
8. 8.🔺 A current of 1.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
10. 10.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
11. 11.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1024 (c) 10 (d) 1000
12. 12.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 33 Ω resistor? (a) yellow-orange-black (b) orange-yellow-black (c) orange-orange-black (d) orange-orange-brown
14. 14.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
15. 15.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
16. 16.🌈 A resistor has the colour bands grey, orange, orange. What is its value (in ohms)?
17. 17.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) a motor (d) an LED
18. 18.📏 How many watts (W) is 3 kW?
19. 19.🧩 Which component boosts a small signal? (a) transistor (b) motor (c) potentiometer (d) buzzer
20. 20.🔺 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
21. 21.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
22. 22.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets bigger (d) gets smaller
23. 23.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
24. 24.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
25. 25.🔺 A current of 1 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
27. 27.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
28. 28.🧮 Resistors of 20 Ω, 68 Ω, 100 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
29. 29.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
30. 30.Which of these is measured in volts (V)? (a) the flow of charge (b) power (c) resistance (d) voltage
31. 31.🧩 Which component senses how hot it is? (a) potentiometer (b) thermistor (c) buzzer (d) diode
32. 32.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 23 Ω resistor? (a) orange-orange-black (b) orange-red-black (c) red-orange-brown (d) red-orange-black
33. 33.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to limit the current (d) to make it brighter
34. 34.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🧩 Which component makes things spin? (a) transistor (b) thermistor (c) motor (d) diode
36. 36.📏 How many milliamperes (mA) is 0.34 A?
37. 37.True or false: the ammeter is joined across a part. (a) True (b) False
38. 38.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
39. 39.True or false: an LED senses how bright it is. (a) False (b) True
40. 40.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R

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