Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 652 · 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.True or false: the voltmeter measures current. (a) True (b) False
2. 2.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it makes a sound (d) it lights brighter
3. 3.🔺 A 1 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
4. 4.🔺 A 10 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
5. 5.💡 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) lights up (b) does not light (c) may burn out
6. 6.True or false: a buzzer limits the current. (a) True (b) False
7. 7.True or false: resistance is measured in ohms (Ω). (a) False (b) True
8. 8.🌈 In the resistor colour code, which number does grey stand for?
9. 9.Which of these is measured in amperes (A)? (a) the flow of charge (b) energy used each second (c) voltage (d) resistance
10. 10.📏 How many amperes (A) is 2040 mA? =
11. 11.🧩 Which component beeps for an alarm? (a) transistor (b) capacitor (c) LED (d) buzzer
12. 12.🧩 Which component boosts a small signal? (a) LDR (b) transistor (c) capacitor (d) LED
13. 13.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
14. 14.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) more than either one (d) always zero
15. 15.🧩 Which component limits the current? (a) capacitor (b) LED (c) resistor (d) diode
16. 16.📏 How many milliamperes (mA) is 0.63 A?
17. 17.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
18. 18.🔺 A current of 1.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
19. 19.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) does not light (c) may burn out
20. 20.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
21. 21.📏 How many milliamperes (mA) is 0.7 A?
22. 22.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
23. 23.📏 Which unit measures resistance? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
24. 24.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = I × R (d) V = R ÷ I
25. 25.True or false: the ammeter is joined in series. (a) True (b) False
26. 26.🌈 A resistor has the colour bands white, orange, orange. What is its value in kilo-ohms (kΩ)? =
27. 27.🌈 A resistor has the colour bands red, red, red. What is its value in kilo-ohms (kΩ)? =
28. 28.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
29. 29.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3500 Ω resistor? (a) orange-green-brown (b) orange-green-red (c) green-orange-red (d) orange-green-orange
31. 31.🔺 A 22.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
32. 32.⚡ An 18 W device works on 6 V. What current does it take (in amperes)? =
33. 33.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
34. 34.🔍 Which is the odd one out? (a) unplug idle chargers (b) use LED lamps (c) switch off empty rooms (d) leave the TV on standby
35. 35.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
36. 36.Which of these is measured in volts (V)? (a) power (b) the flow of charge (c) the push of a cell (d) current
37. 37.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) zero (d) stay the same
38. 38.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
39. 39.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
40. 40.True or false: the voltmeter measures voltage. (a) True (b) False

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