Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 268 · 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.🔺 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
2. 2.🌈 A resistor has the colour bands yellow, grey, brown. What is its value (in ohms)?
3. 3.🧮 Resistors of 10 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
4. 4.True or false: a thermistor has coloured bands. (a) True (b) False
5. 5.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) a candle (d) an oil lamp
6. 6.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1700 Ω resistor? (a) brown-violet-brown (b) brown-violet-orange (c) brown-violet-red (d) violet-brown-red
7. 7.🔺 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
8. 8.🌈 A resistor has the colour bands blue, red, red. What is its value (in ohms)?
9. 9.Which of these is measured in watts (W)? (a) energy used each second (b) the flow of charge (c) how much a part resists (d) voltage
10. 10.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
11. 11.True or false: energy used each second is measured in volts (V). (a) True (b) False
12. 12.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
13. 13.📏 How many ohms (Ω) is 9.4 kΩ?
14. 14.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
15. 15.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
16. 16.📏 Which unit measures power? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
17. 17.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
18. 18.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
20. 20.🧮 Resistors of 220 Ω, 33 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
21. 21.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
22. 22.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔍 Which is the odd one out? (a) use old filament bulbs (b) run fans in empty rooms (c) leave fridge door open (d) use daylight to read
24. 24.🔍 Which is the odd one out? (a) iron one shirt at a time (b) close the fridge quickly (c) run fans in empty rooms (d) leave fridge door open
25. 25.Which of these wastes electricity? (a) close the fridge quickly (b) set the AC to 24 °C (c) unplug idle chargers (d) leave fridge door open
26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 43000 Ω resistor? (a) orange-yellow-orange (b) yellow-orange-red (c) yellow-orange-yellow (d) yellow-orange-orange
27. 27.🔺 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
28. 28.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1024 (c) 10 (d) 1000
29. 29.🧮 A 1.8 V battery is joined to 6 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
30. 30.🔺 A current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
32. 32.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
33. 33.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
34. 34.⚡ A 1.5 W device works on 6 V. What current does it take (in amperes)? =
35. 35.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
36. 36.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
37. 37.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
38. 38.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) bigger (d) stay the same
39. 39.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
40. 40.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) the flow of water (c) a bigger tank (d) the water pressure

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