Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 695 · 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 unit measures resistance? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
2. 2.True or false: an LDR makes a beeping sound. (a) True (b) False
3. 3.🔍 Which is the odd one out? (a) switch off empty rooms (b) iron one shirt at a time (c) use LED lamps (d) unplug idle chargers
4. 4.📏 Which unit measures the push of a cell? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
5. 5.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
6. 6.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
7. 7.🔺 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
8. 8.🔺 A current of 2 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.🔍 Which is the odd one out? (a) leave the TV on standby (b) run fans in empty rooms (c) use LED lamps (d) use old filament bulbs
10. 10.🌈 A resistor has the colour bands brown, black, yellow. What is its value in kilo-ohms (kΩ)? =
11. 11.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
12. 12.What does a buzzer do? (a) turns a fan or wheels (b) has coloured bands (c) makes a beeping sound (d) limits the current
13. 13.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
14. 14.🧩 Which component limits the current? (a) diode (b) potentiometer (c) fuse (d) resistor
15. 15.⚡ A 6 W device works on 24 V. What current does it take (in amperes)? =
16. 16.🌈 In the resistor colour code, which number does red stand for?
17. 17.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
18. 18.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🧮 A 100 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
20. 20.🔺 A current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
21. 21.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
22. 22.📏 How many kilo-ohms (kΩ) is 5400 Ω? =
23. 23.🧩 Which component makes things spin? (a) capacitor (b) motor (c) fuse (d) transistor
24. 24.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a diode (c) a resistor (d) a capacitor
25. 25.🧮 Resistors of 22 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
27. 27.📏 Which unit measures voltage? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
28. 28.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
29. 29.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an oil lamp (c) a candle (d) an LED lamp
30. 30.🌈 A resistor has the colour bands grey, violet, brown. What is its value (in ohms)?
31. 31.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
32. 32.🔺 A 3 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
33. 33.Which of these is measured in watts (W)? (a) voltage (b) how much a part resists (c) the push of a cell (d) energy used each second
34. 34.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) energy used each second (d) the size of a cell
35. 35.🧩 Which component is a resistance knob? (a) fuse (b) LDR (c) potentiometer (d) capacitor
36. 36.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
37. 37.True or false: a transistor boosts a small signal. (a) False (b) True
38. 38.⚡ A device works on 5 V and takes 0.5 A. What is its power (in watts)? =
39. 39.🔺 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
40. 40.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)

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