Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 391 · 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 has coloured bands? (a) resistor (b) motor (c) transistor (d) LDR
2. 2.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
3. 3.What does a thermistor do? (a) limits the current (b) boosts a small signal (c) senses how hot it is (d) turns a fan or wheels
4. 4.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a diode (c) a capacitor (d) a resistor
5. 5.True or false: the voltmeter measures current. (a) True (b) False
6. 6.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = R ÷ V (c) I = V ÷ R (d) I = V + R
7. 7.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
8. 8.🧮 A 2.8 V battery is joined to 10 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
9. 9.🔺 A current of 1 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 100 (c) 10 (d) 1000
11. 11.🔍 Which is the odd one out? (a) use LED lamps (b) use old filament bulbs (c) leave the TV on standby (d) leave fridge door open
12. 12.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
13. 13.🧮 Resistors of 33 Ω, 470 Ω, 68 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
14. 14.🧩 Which component beeps for an alarm? (a) buzzer (b) LDR (c) transistor (d) LED
15. 15.🔺 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
16. 16.True or false: power is measured in watts (W). (a) False (b) True
17. 17.📏 Which unit measures voltage? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
18. 18.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
19. 19.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
20. 20.📏 How many kilo-ohms (kΩ) is 7600 Ω? =
21. 21.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) becomes zero (d) gets smaller
22. 22.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
23. 23.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
24. 24.What does an LED do? (a) limits the current (b) has coloured bands (c) turns a fan or wheels (d) glows using little power
25. 25.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
26. 26.Which of these wastes electricity? (a) leave fridge door open (b) set the AC to 24 °C (c) switch off empty rooms (d) use daylight to read
27. 27.🌈 In the resistor colour code, which number does grey stand for?
28. 28.🧾 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
29. 29.What does a transistor do? (a) boosts a small signal (b) senses how hot it is (c) stores a little charge (d) senses how bright it is
30. 30.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
31. 31.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
32. 32.🔺 A current of 50 mA flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.True or false: the push of a cell is measured in volts (V). (a) False (b) True
34. 34.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
35. 35.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 50 % (d) 5 %
36. 36.🔺 A 15 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
37. 37.🔺 A current of 0.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
38. 38.Which of these is measured in ohms (Ω)? (a) power (b) the flow of charge (c) how much a part resists (d) the push of a cell
39. 39.True or false: a capacitor stores a little charge. (a) False (b) True
40. 40.🧩 Which component senses how hot it is? (a) buzzer (b) LDR (c) transistor (d) thermistor

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