Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 258 · 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.🌈 In the resistor colour code, which number does green stand for?
2. 2.🌈 A resistor has the colour bands blue, blue, yellow. What is its value in kilo-ohms (kΩ)? =
3. 3.🧾 A 500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
4. 4.Which of these is measured in watts (W)? (a) current (b) energy used each second (c) how much a part resists (d) voltage
5. 5.🌈 In the resistor colour code, which number does red stand for?
6. 6.True or false: the ammeter measures voltage. (a) True (b) False
7. 7.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
8. 8.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) more than either one (d) their sum
9. 9.🔺 A current of 2 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
11. 11.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
12. 12.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.What does a buzzer do? (a) is a resistance knob (b) limits the current (c) has coloured bands (d) beeps for an alarm
14. 14.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
15. 15.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
16. 16.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
17. 17.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
18. 18.🌈 A resistor has the colour bands orange, red, yellow. What is its value in kilo-ohms (kΩ)? =
19. 19.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
20. 20.True or false: a fuse blows if current is high. (a) True (b) False
21. 21.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
22. 22.🌈 A resistor has the colour bands green, orange, orange. What is its value in kilo-ohms (kΩ)? =
23. 23.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) the gold band (d) any band
24. 24.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
25. 25.🧩 Which component has coloured bands? (a) buzzer (b) resistor (c) capacitor (d) transistor
26. 26.🌈 A resistor has the colour bands red, brown, orange. What is its value (in ohms)?
27. 27.📏 How many amperes (A) is 260 mA? =
28. 28.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
29. 29.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) energy used each second (d) the colour of light
30. 30.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
31. 31.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
32. 32.🔺 A current of 25 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 100 (c) 1000 (d) 60
34. 34.🔺 A current of 20 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🔺 A 4.7 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
36. 36.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.📏 How many ohms (Ω) is 2.9 kΩ?
38. 38.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I + R (c) V = R ÷ I (d) V = I ÷ R
39. 39.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V × I (c) R = V + I (d) R = V ÷ I
40. 40.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False

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