Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 655 · 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 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🔺 A current of 2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🔺 A current of 1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) smaller (d) zero
5. 5.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = R ÷ I (d) V = I × R
6. 6.💡 An LED is joined to a 6 V battery with no 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
7. 7.🧮 Resistors of 50 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
8. 8.Which of these saves electricity? (a) iron one shirt at a time (b) use old filament bulbs (c) use daylight to read (d) leave the TV on standby
9. 9.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
10. 10.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
11. 11.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
12. 12.🔺 A 9.4 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
13. 13.Which of these wastes electricity? (a) leave fridge door open (b) switch off empty rooms (c) use LED lamps (d) use daylight to read
14. 14.🧩 Which component stores a little charge? (a) resistor (b) potentiometer (c) LDR (d) capacitor
15. 15.📏 Which unit measures how much a part resists? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
16. 16.🧮 Resistors of 330 Ω, 50 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
17. 17.🔺 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
18. 18.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
19. 19.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
20. 20.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.🧩 Which component blows if current is high? (a) diode (b) buzzer (c) fuse (d) LDR
22. 22.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
24. 24.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) gets smaller (d) stays the same
25. 25.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
26. 26.True or false: the ammeter is joined across a part. (a) True (b) False
27. 27.🌈 A resistor has the colour bands violet, blue, yellow. What is its value in kilo-ohms (kΩ)? =
28. 28.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
29. 29.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 97000 Ω resistor? (a) white-violet-red (b) white-violet-orange (c) white-violet-yellow (d) violet-white-orange
31. 31.🌈 A resistor has the colour bands white, blue, red. What is its value (in ohms)?
32. 32.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🧮 Resistors of 47 Ω, 220 Ω, 10 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
34. 34.🌈 A resistor has the colour bands white, violet, red. What is its value (in ohms)?
35. 35.True or false: a motor smooths a wobbly supply. (a) True (b) False
36. 36.📏 Which unit measures the flow of charge? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
37. 37.🧮 A 68 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)?
38. 38.🔺 A current of 0.2 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
39. 39.🔍 Which is the odd one out? (a) leave the TV on standby (b) close the fridge quickly (c) leave fridge door open (d) use old filament bulbs
40. 40.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I

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