Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 279 · 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.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
2. 2.📏 How many kilo-ohms (kΩ) is 9300 Ω? =
3. 3.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
4. 4.⚡ 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
5. 5.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 50 % (d) 5 %
7. 7.True or false: a potentiometer limits the current. (a) False (b) True
8. 8.📏 How many kilo-ohms (kΩ) is 2300 Ω? =
9. 9.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) a resistor (d) an LED
10. 10.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
12. 12.What does a resistor do? (a) turns a fan or wheels (b) limits the current (c) glows using little power (d) makes things spin
13. 13.🧮 A 220 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)?
14. 14.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
15. 15.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I
16. 16.True or false: a motor limits the current. (a) False (b) True
17. 17.🔺 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
18. 18.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
19. 19.🧮 A 10 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
20. 20.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
21. 21.True or false: energy used each second is measured in volts (V). (a) True (b) False
22. 22.🧮 A 1.4 V battery is joined to 3 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
23. 23.🧮 Resistors of 330 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
24. 24.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🔺 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
26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 32 Ω resistor? (a) orange-red-black (b) red-orange-black (c) yellow-red-black (d) orange-red-brown
27. 27.🧾 A 250 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
28. 28.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?
29. 29.⚡ A device works on 5 V and takes 0.1 A. What is its power (in watts)? =
30. 30.🧩 Which component blows if current is high? (a) capacitor (b) resistor (c) potentiometer (d) fuse
31. 31.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
32. 32.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
33. 33.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
34. 34.True or false: a buzzer makes a beeping sound. (a) True (b) False
35. 35.📏 Which unit measures current? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
36. 36.Which of these wastes electricity? (a) use daylight to read (b) iron one shirt at a time (c) switch off empty rooms (d) set the AC to 24 °C
37. 37.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
38. 38.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) may burn out (c) does not light
39. 39.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.💡 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)?

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