Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 320 · 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 home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
2. 2.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
3. 3.🔍 Which is the odd one out? (a) unplug idle chargers (b) iron one shirt at a time (c) use LED lamps (d) close the fridge quickly
4. 4.📏 Which unit measures energy used each second? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
5. 5.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
6. 6.🧩 Which component makes things spin? (a) resistor (b) motor (c) diode (d) capacitor
7. 7.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the pipe colour (c) the tap handle (d) the water pressure
8. 8.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🔺 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
10. 10.📏 How many watts (W) is 4.9 kW?
11. 11.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
12. 12.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it does not light (c) it changes colour (d) it makes a sound
13. 13.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🧩 Which component beeps for an alarm? (a) buzzer (b) LED (c) capacitor (d) LDR
15. 15.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %
16. 16.True or false: the ammeter measures voltage. (a) False (b) True
17. 17.💡 What does LED stand for? (a) light-emitting diode (b) low energy device (c) large electric dial (d) light energy dial
18. 18.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
19. 19.True or false: how much a part resists is measured in volts (V). (a) False (b) True
20. 20.🧮 A 3.75 V battery is joined to 3 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
21. 21.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
22. 22.📏 Which unit measures voltage? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
23. 23.🌈 A resistor has the colour bands brown, green, orange. What is its value in kilo-ohms (kΩ)? =
24. 24.True or false: resistance is measured in ohms (Ω). (a) True (b) False
25. 25.📏 Which unit measures how much a part resists? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
26. 26.🔺 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
27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 32 Ω resistor? (a) orange-red-black (b) orange-red-brown (c) yellow-red-black (d) red-orange-black
28. 28.What does a resistor do? (a) limits the current (b) turns a fan or wheels (c) smooths a wobbly supply (d) glows using little power
29. 29.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
31. 31.🔺 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
32. 32.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
33. 33.Which of these is measured in watts (W)? (a) the push of a cell (b) the flow of charge (c) resistance (d) energy used each second
34. 34.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
35. 35.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
36. 36.🌈 A resistor has the colour bands white, green, brown. What is its value (in ohms)?
37. 37.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
38. 38.🧮 A 3 V battery is joined to 2 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
39. 39.🧮 A 10 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
40. 40.🌈 A resistor has the colour bands violet, white, black. What is its value (in ohms)?

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