Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 777 · 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.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
2. 2.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1000 (c) 10 (d) 1024
3. 3.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
4. 4.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
5. 5.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the length of a wire (d) the size of a cell
6. 6.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) any band (d) the one nearest an end
7. 7.🔺 A current of 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) leave the TV on standby (c) use LED lamps (d) close the fridge quickly
10. 10.🧾 A 2000 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
11. 11.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
12. 12.🌈 A resistor has the colour bands grey, red, orange. What is its value in kilo-ohms (kΩ)? =
13. 13.📏 Which unit measures resistance? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
14. 14.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
15. 15.True or false: a motor turns a fan or wheels. (a) False (b) True
16. 16.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
19. 19.Which of these wastes electricity? (a) leave the TV on standby (b) use daylight to read (c) set the AC to 24 °C (d) unplug idle chargers
20. 20.📏 How many milliamperes (mA) is 1.25 A?
21. 21.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
22. 22.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
23. 23.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = R ÷ I (c) V = I ÷ R (d) V = I × R
24. 24.🔺 A current of 25 mA flows when 5.5 V is joined across a resistor. What is its resistance (in ohms)?
25. 25.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
26. 26.🔺 A current of 0.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
27. 27.Which of these wastes electricity? (a) use LED lamps (b) run fans in empty rooms (c) unplug idle chargers (d) switch off empty rooms
28. 28.What does a potentiometer do? (a) senses how bright it is (b) turns a fan or wheels (c) is a resistance knob (d) senses how hot it is
29. 29.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
30. 30.🔺 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
31. 31.📏 How many amperes (A) is 2570 mA? =
32. 32.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
33. 33.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
35. 35.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
36. 36.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it lights brighter (c) it makes a sound (d) it does not light
37. 37.🌈 A resistor has the colour bands yellow, white, yellow. What is its value in kilo-ohms (kΩ)? =
38. 38.🌈 A resistor has the colour bands yellow, blue, red. What is its value in kilo-ohms (kΩ)? =
39. 39.🌈 A resistor has the colour bands white, brown, black. What is its value (in ohms)?
40. 40.True or false: the push of a cell is measured in amperes (A). (a) True (b) False

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