Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 283 · 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 component senses how hot it is? (a) diode (b) LED (c) resistor (d) thermistor
2. 2.🌈 In the resistor colour code, which number does orange stand for?
3. 3.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a motor (d) a fuse
4. 4.What does a potentiometer do? (a) beeps for an alarm (b) smooths a wobbly supply (c) blows if current is high (d) is a resistance knob
5. 5.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
6. 6.🔺 A 0.4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
7. 7.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I ÷ R (c) V = I × R (d) V = I + R
8. 8.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
9. 9.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the length of a wire (d) the size of a cell
10. 10.🔍 Which is the odd one out? (a) unplug idle chargers (b) use LED lamps (c) leave the TV on standby (d) switch off empty rooms
11. 11.🔺 A 15 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
12. 12.🧮 Resistors of 150 Ω, 150 Ω, 22 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
13. 13.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
14. 14.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.True or false: a diode makes things spin. (a) False (b) True
16. 16.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🔺 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
18. 18.🔺 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
19. 19.💡 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?
20. 20.🔺 A current of 3 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
21. 21.🔺 A 23.5 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
22. 22.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
23. 23.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
24. 24.📏 How many ohms (Ω) is 3.7 kΩ?
25. 25.📏 How many watts (W) is 3.2 kW?
26. 26.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🧩 Which component is a resistance knob? (a) potentiometer (b) transistor (c) fuse (d) thermistor
28. 28.📏 How many kilowatts (kW) is 1100 W? =
29. 29.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) any band (d) the gold band
30. 30.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) gets bigger (d) becomes zero
31. 31.Which of these wastes electricity? (a) switch off empty rooms (b) set the AC to 24 °C (c) unplug idle chargers (d) iron one shirt at a time
32. 32.🔍 Which is the odd one out? (a) run fans in empty rooms (b) iron one shirt at a time (c) leave the TV on standby (d) use LED lamps
33. 33.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
34. 34.Which of these is measured in watts (W)? (a) voltage (b) resistance (c) current (d) energy used each second
35. 35.What does a motor do? (a) boosts a small signal (b) turns a fan or wheels (c) blows if current is high (d) senses how bright it is
36. 36.True or false: the ammeter is joined in series. (a) True (b) False
37. 37.🌈 A resistor has the colour bands orange, black, yellow. What is its value in kilo-ohms (kΩ)? =
38. 38.True or false: a diode lets current go one way. (a) False (b) True
39. 39.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) an oil lamp (c) a filament bulb (d) a candle
40. 40.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False

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