Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 374 · 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 water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
2. 2.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the pipe colour (c) the water pressure (d) the flow of water
3. 3.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 88 Ω resistor? (a) grey-grey-black (b) grey-grey-brown (c) grey-white-black (d) white-grey-black
5. 5.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
6. 6.🔺 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
7. 7.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
8. 8.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = I × R (d) V = R ÷ I
10. 10.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
11. 11.📏 How many milliamperes (mA) is 2.82 A?
12. 12.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
13. 13.⚡ A device works on 9 V and takes 0.25 A. What is its power (in watts)? =
14. 14.Which of these is measured in watts (W)? (a) how much a part resists (b) the push of a cell (c) resistance (d) energy used each second
15. 15.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) low energy device (d) light-emitting diode
16. 16.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
19. 19.🧩 Which component makes things spin? (a) motor (b) potentiometer (c) capacitor (d) LED
20. 20.🧾 A 100 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
21. 21.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a diode (c) a resistor (d) a capacitor
22. 22.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a resistor (d) a motor
23. 23.🧩 Which component blows if current is high? (a) LED (b) fuse (c) thermistor (d) diode
24. 24.🔺 A 10 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
25. 25.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
26. 26.📏 How many watts (W) is 2.7 kW?
27. 27.What does a capacitor do? (a) stores a little charge (b) blows if current is high (c) senses how bright it is (d) makes a beeping sound
28. 28.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
29. 29.🔺 A 6 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
30. 30.🌈 A resistor has the colour bands violet, yellow, red. What is its value (in ohms)?
31. 31.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
32. 32.🧮 A 330 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
33. 33.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
34. 34.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V × I (c) R = V + I (d) R = I ÷ V
35. 35.🔺 A 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
36. 36.🧾 A 50 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
37. 37.🔺 A 3 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
38. 38.True or false: a potentiometer is a resistance knob. (a) False (b) True
39. 39.🧮 A 330 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
40. 40.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)

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