Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 704 · 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.📏 How many milliamperes (mA) is 2.89 A?
2. 2.📏 Which unit measures resistance? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
3. 3.Which of these is measured in volts (V)? (a) energy used each second (b) voltage (c) current (d) the flow of charge
4. 4.🧾 A 250 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
5. 5.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
6. 6.🔺 A 23.5 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
7. 7.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
8. 8.Which of these is measured in watts (W)? (a) resistance (b) how much a part resists (c) energy used each second (d) voltage
9. 9.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3000 Ω resistor? (a) orange-black-brown (b) yellow-orange-red (c) orange-black-red (d) orange-black-orange
10. 10.🧮 A 47 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
11. 11.🧩 Which component glows using little power? (a) LED (b) resistor (c) LDR (d) fuse
12. 12.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
13. 13.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
14. 14.🔺 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
15. 15.🌈 A resistor has the colour bands green, blue, brown. What is its value (in ohms)?
16. 16.True or false: an LDR has coloured bands. (a) True (b) False
17. 17.🧩 Which component smooths a wobbly supply? (a) LDR (b) capacitor (c) diode (d) resistor
18. 18.🔍 Which is the odd one out? (a) use LED lamps (b) switch off empty rooms (c) iron one shirt at a time (d) use daylight to read
19. 19.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
20. 20.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
21. 21.🧩 Which component is a resistance knob? (a) diode (b) LDR (c) buzzer (d) potentiometer
22. 22.🌈 A resistor has the colour bands orange, red, brown. What is its value (in ohms)?
23. 23.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
25. 25.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it lights brighter (d) it does not light
26. 26.🌈 A resistor has the colour bands blue, black, red. What is its value in kilo-ohms (kΩ)? =
27. 27.True or false: an LED makes a beeping sound. (a) True (b) False
28. 28.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
29. 29.What does a diode do? (a) beeps for an alarm (b) makes things spin (c) lets current go one way (d) turns a fan or wheels
30. 30.Which of these is measured in volts (V)? (a) the push of a cell (b) current (c) the flow of charge (d) resistance
31. 31.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
32. 32.🧾 A 200 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
33. 33.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
34. 34.True or false: current is measured in amperes (A). (a) True (b) False
35. 35.🧩 Which component blows if current is high? (a) thermistor (b) LED (c) fuse (d) resistor
36. 36.🔺 A current of 2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
37. 37.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the pipe colour (c) the water tank lid (d) the water pressure
38. 38.🧩 Which part changes electrical energy into sound? (a) a diode (b) a resistor (c) a buzzer (d) a capacitor
39. 39.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
40. 40.🌈 A resistor has the colour bands violet, brown, red. What is its value (in ohms)?

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