Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 405 · 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.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 100 (c) 1000 (d) 10
2. 2.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
3. 3.📏 How many kilowatts (kW) is 950 W? =
4. 4.🧮 Resistors of 470 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.🔺 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
6. 6.📏 How many milliamperes (mA) is 1.75 A?
7. 7.True or false: the ammeter measures current. (a) False (b) True
8. 8.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
9. 9.⚡ A 4.5 W device works on 9 V. What current does it take (in amperes)? =
10. 10.🧮 A 220 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
11. 11.💡 An LED is joined to a 6 V battery with no 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
12. 12.📏 How many amperes (A) is 1530 mA? =
13. 13.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a resistor (d) a motor
14. 14.🔺 A current of 3 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
16. 16.🔺 A 1.5 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
17. 17.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
18. 18.True or false: a potentiometer makes things spin. (a) False (b) True
19. 19.🔺 A 2 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
20. 20.🧩 Which component turns a fan or wheels? (a) motor (b) capacitor (c) LED (d) LDR
21. 21.🌈 A resistor has the colour bands blue, black, red. What is its value in kilo-ohms (kΩ)? =
22. 22.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
23. 23.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
24. 24.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to limit the current (d) to change its colour
25. 25.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 520 Ω resistor? (a) green-red-black (b) green-red-brown (c) red-green-brown (d) green-red-red
27. 27.🧮 Resistors of 150 Ω, 330 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
28. 28.💡 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
29. 29.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
30. 30.True or false: the ammeter measures voltage. (a) True (b) False
31. 31.🌈 A resistor has the colour bands green, black, yellow. What is its value in kilo-ohms (kΩ)? =
32. 32.Which of these is measured in volts (V)? (a) voltage (b) power (c) resistance (d) energy used each second
33. 33.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
34. 34.🧩 Which component lets current go one way? (a) diode (b) LDR (c) capacitor (d) transistor
35. 35.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
36. 36.💡 An LED is joined to a 3 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
37. 37.🔺 A 3 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
38. 38.📏 Which unit measures voltage? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
39. 39.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
40. 40.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1024 (c) 10 (d) 1000

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