Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 39 · 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 ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 100 (c) 1024 (d) 1000
2. 2.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) zero (d) stay the same
3. 3.🔺 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
4. 4.💡 What does LED stand for? (a) low energy device (b) light-emitting diode (c) light energy dial (d) large electric dial
5. 5.🧩 Which part changes electrical energy into sound? (a) a diode (b) a buzzer (c) a capacitor (d) a resistor
6. 6.🔍 Which is the odd one out? (a) use daylight to read (b) leave fridge door open (c) iron one shirt at a time (d) leave the TV on standby
7. 7.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to make it brighter (c) to limit the current (d) to store charge
8. 8.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
9. 9.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
10. 10.True or false: the push of a cell is measured in ohms (Ω). (a) False (b) True
11. 11.🔺 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
12. 12.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
13. 13.🧮 Resistors of 10 Ω, 10 Ω, 50 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
14. 14.True or false: an LDR is a resistance knob. (a) True (b) False
15. 15.What does a potentiometer do? (a) stores a little charge (b) is a resistance knob (c) has coloured bands (d) limits the current
16. 16.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
17. 17.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the pipe colour (c) the flow of water (d) a narrow pipe
18. 18.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
19. 19.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🌈 A resistor has the colour bands brown, violet, red. What is its value (in ohms)?
21. 21.🧮 Resistors of 470 Ω, 22 Ω, 33 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7700 Ω resistor? (a) violet-violet-brown (b) violet-violet-orange (c) violet-grey-red (d) violet-violet-red
23. 23.🧮 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
24. 24.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 50 % (d) 5 %
26. 26.🌈 In the resistor colour code, which number does white stand for?
27. 27.🧮 A 3.6 V battery is joined to 12 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
28. 28.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
29. 29.🧮 A 4 V battery is joined to 8 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
30. 30.⚡ A device works on 24 V and takes 2 A. What is its power (in watts)? =
31. 31.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
32. 32.Which of these is measured in ohms (Ω)? (a) resistance (b) power (c) energy used each second (d) voltage
33. 33.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
34. 34.What does a capacitor do? (a) senses how bright it is (b) turns a fan or wheels (c) smooths a wobbly supply (d) boosts a small signal
35. 35.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
36. 36.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
37. 37.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
38. 38.🧮 Resistors of 22 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
39. 39.🧮 Resistors of 10 Ω, 20 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
40. 40.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?

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