Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 407 · 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) 1024 (b) 100 (c) 1000 (d) 10
2. 2.⚡ A 12 W device works on 6 V. What current does it take (in amperes)? =
3. 3.True or false: the ammeter measures voltage. (a) True (b) False
4. 4.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to make it brighter (d) to store charge
5. 5.🧾 A 500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
6. 6.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
7. 7.⚡ A 24 W device works on 12 V. What current does it take (in amperes)? =
8. 8.Which of these is measured in volts (V)? (a) power (b) resistance (c) the flow of charge (d) voltage
9. 9.📏 How many kilowatts (kW) is 4400 W? =
10. 10.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the flow of water (c) the pipe colour (d) the water pressure
11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 740 Ω resistor? (a) violet-yellow-black (b) yellow-violet-brown (c) violet-yellow-red (d) violet-yellow-brown
12. 12.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a buzzer (d) a diode
13. 13.⚡ A device works on 24 V and takes 0.25 A. What is its power (in watts)? =
14. 14.🧮 A 47 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
15. 15.Which of these wastes electricity? (a) use daylight to read (b) switch off empty rooms (c) leave the TV on standby (d) use LED lamps
16. 16.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) always zero (d) their sum
17. 17.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
18. 18.💡 A red LED uses 2 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
19. 19.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 360 Ω resistor? (a) orange-blue-black (b) orange-blue-brown (c) orange-blue-red (d) blue-orange-brown
21. 21.🔺 A current of 1.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
22. 22.🔺 A current of 0.1 A flows when 0.2 V is joined across a resistor. What is its resistance (in ohms)?
23. 23.True or false: to leave the TV on standby saves electricity. (a) False (b) True
24. 24.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
25. 25.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
26. 26.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
27. 27.🔺 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
28. 28.🔍 Which is the odd one out? (a) unplug idle chargers (b) use old filament bulbs (c) iron one shirt at a time (d) run fans in empty rooms
29. 29.🧮 A 470 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
30. 30.🌈 A resistor has the colour bands brown, grey, yellow. What is its value in kilo-ohms (kΩ)? =
31. 31.🧮 A 1.6 V battery is joined to 10 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
32. 32.📏 How many amperes (A) is 340 mA? =
33. 33.🧮 Resistors of 470 Ω, 220 Ω, 330 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
34. 34.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = R ÷ V (d) I = V ÷ R
35. 35.🧩 Which component stores a little charge? (a) LDR (b) thermistor (c) capacitor (d) resistor
36. 36.📏 How many kilo-ohms (kΩ) is 6100 Ω? =
37. 37.True or false: how much a part resists is measured in watts (W). (a) True (b) False
38. 38.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 32 Ω resistor? (a) orange-red-black (b) yellow-red-black (c) red-orange-black (d) orange-red-brown

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