Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 796 · 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 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.📏 Which unit measures energy used each second? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
3. 3.🌈 A resistor has the colour bands violet, black, yellow. What is its value in kilo-ohms (kΩ)? =
4. 4.Which of these is measured in volts (V)? (a) current (b) the push of a cell (c) power (d) energy used each second
5. 5.🧩 Which component senses how hot it is? (a) thermistor (b) potentiometer (c) buzzer (d) transistor
6. 6.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V × I (d) R = V ÷ I
7. 7.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
8. 8.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
9. 9.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
10. 10.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
11. 11.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
12. 12.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
13. 13.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
14. 14.True or false: an LED makes things spin. (a) True (b) False
15. 15.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
16. 16.🌈 In the resistor colour code, which number does red stand for?
17. 17.🌈 A resistor has the colour bands brown, grey, red. What is its value in kilo-ohms (kΩ)? =
18. 18.🧮 A 7.5 V battery is joined to 3 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
19. 19.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
22. 22.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
23. 23.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
24. 24.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.⚡ A device works on 24 V and takes 0.25 A. What is its power (in watts)? =
26. 26.🔺 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
27. 27.🔍 Which is the odd one out? (a) iron one shirt at a time (b) leave fridge door open (c) leave the TV on standby (d) use LED lamps
28. 28.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light energy dial (d) light-emitting diode
29. 29.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
30. 30.🧩 Which component limits the current? (a) potentiometer (b) thermistor (c) resistor (d) motor
31. 31.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
32. 32.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
33. 33.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
34. 34.Which of these saves electricity? (a) iron one shirt at a time (b) leave fridge door open (c) unplug idle chargers (d) use old filament bulbs
35. 35.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) zero (d) smaller
36. 36.🌈 A resistor has the colour bands grey, black, brown. What is its value (in ohms)?
37. 37.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
38. 38.True or false: the ammeter measures voltage. (a) False (b) True
39. 39.🔺 A 45 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
40. 40.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) the size of a cell (d) energy used each second

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