Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 938 · 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 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
2. 2.🌈 A resistor has the colour bands yellow, black, orange. What is its value in kilo-ohms (kΩ)? =
3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9900 Ω resistor? (a) white-white-orange (b) white-black-red (c) white-white-brown (d) white-white-red
4. 4.🔺 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
5. 5.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
6. 6.🔍 Which is the odd one out? (a) use LED lamps (b) switch off empty rooms (c) use daylight to read (d) leave fridge door open
7. 7.🧮 A 1.8 V battery is joined to 5 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 210 Ω resistor? (a) red-brown-black (b) red-brown-red (c) brown-red-brown (d) red-brown-brown
9. 9.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 73000 Ω resistor? (a) violet-orange-yellow (b) violet-orange-orange (c) violet-orange-red (d) orange-violet-orange
10. 10.True or false: a diode smooths a wobbly supply. (a) False (b) True
11. 11.True or false: a buzzer makes a beeping sound. (a) False (b) True
12. 12.🧩 Which component beeps for an alarm? (a) capacitor (b) buzzer (c) LED (d) motor
13. 13.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
14. 14.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
15. 15.True or false: a buzzer glows using little power. (a) True (b) False
16. 16.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
17. 17.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
18. 18.🔺 A current of 1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) measure heat (d) spin a wheel
20. 20.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) light energy dial (d) low energy device
21. 21.📏 How many kilo-ohms (kΩ) is 2900 Ω? =
22. 22.🔺 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
23. 23.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
24. 24.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🌈 A resistor has the colour bands grey, green, black. What is its value (in ohms)?
26. 26.Which of these is measured in amperes (A)? (a) current (b) voltage (c) resistance (d) the push of a cell
27. 27.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
28. 28.True or false: energy used each second is measured in amperes (A). (a) True (b) False
29. 29.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
30. 30.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
31. 31.🧮 A 2 V battery is joined to 5 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
32. 32.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
34. 34.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 ampere (d) 1 watt
35. 35.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
36. 36.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
37. 37.📏 Which unit measures voltage? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
38. 38.🧾 A 200 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
39. 39.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
40. 40.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?

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