Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 213 · 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.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
2. 2.⚡ A 13.5 W device works on 9 V. What current does it take (in amperes)? =
3. 3.📏 How many kilo-ohms (kΩ) is 8600 Ω? =
4. 4.🔺 A 4 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
5. 5.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the flow of water (c) a narrow pipe (d) the water pressure
6. 6.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
7. 7.Which of these is measured in amperes (A)? (a) power (b) how much a part resists (c) the push of a cell (d) current
8. 8.What does a thermistor do? (a) turns a fan or wheels (b) blows if current is high (c) senses how hot it is (d) stores a little charge
9. 9.🔺 A 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
10. 10.🧮 Resistors of 20 Ω, 100 Ω, 50 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.⚡ 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
12. 12.What does a capacitor do? (a) stores a little charge (b) is a resistance knob (c) senses how hot it is (d) lets current go one way
13. 13.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it lights brighter (d) it does not light
14. 14.🔺 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
15. 15.📏 How many watts (W) is 3.8 kW?
16. 16.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one
18. 18.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🔺 A 2 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
22. 22.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
23. 23.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
24. 24.🌈 A resistor has the colour bands red, brown, black. What is its value (in ohms)?
25. 25.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🌈 A resistor has the colour bands red, grey, orange. What is its value in kilo-ohms (kΩ)? =
27. 27.🔺 A 36 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
28. 28.📏 Which unit measures energy used each second? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
29. 29.What does a fuse do? (a) blows if current is high (b) beeps for an alarm (c) is a resistance knob (d) senses how hot it is
30. 30.🔺 A 16 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
31. 31.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
32. 32.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = R ÷ V (d) I = V ÷ R
33. 33.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🌈 A resistor has the colour bands white, orange, yellow. What is its value in kilo-ohms (kΩ)? =
35. 35.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
36. 36.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
37. 37.True or false: to set the AC to 24 °C wastes electricity. (a) False (b) True
38. 38.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🌈 In the resistor colour code, which number does black stand for?
40. 40.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity

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