Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 951 · 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 68 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
2. 2.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) gets bigger (d) becomes zero
4. 4.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
5. 5.🌈 In the resistor colour code, which number does white stand for?
6. 6.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
7. 7.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one
8. 8.🧩 Which component has coloured bands? (a) LED (b) resistor (c) motor (d) thermistor
9. 9.🔺 A current of 10 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
11. 11.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
12. 12.🔺 A current of 3 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
13. 13.What does a motor do? (a) smooths a wobbly supply (b) stores a little charge (c) limits the current (d) makes things spin
14. 14.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
15. 15.True or false: to use daylight to read wastes electricity. (a) False (b) True
16. 16.📏 How many watts (W) is 3.3 kW?
17. 17.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
19. 19.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.🌈 A resistor has the colour bands blue, grey, orange. What is its value in kilo-ohms (kΩ)? =
21. 21.True or false: the ammeter measures voltage. (a) True (b) False
22. 22.🌈 A resistor has the colour bands red, brown, orange. What is its value (in ohms)?
23. 23.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) low energy device (d) light-emitting diode
24. 24.🌈 A resistor has the colour bands orange, green, red. What is its value in kilo-ohms (kΩ)? =
25. 25.🧮 Resistors of 100 Ω, 20 Ω, 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
26. 26.🧮 A 6.5 V battery is joined to 5 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
27. 27.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
28. 28.🔍 Which is the odd one out? (a) run fans in empty rooms (b) use LED lamps (c) use daylight to read (d) close the fridge quickly
29. 29.Which of these is measured in watts (W)? (a) resistance (b) energy used each second (c) voltage (d) current
30. 30.🧩 Which component is a resistance knob? (a) buzzer (b) potentiometer (c) LED (d) LDR
31. 31.📏 How many kilowatts (kW) is 4100 W? =
32. 32.🧮 A 1.5 V battery is joined to 4 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
33. 33.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) an LED lamp (d) a filament bulb
34. 34.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
35. 35.🌈 A resistor has the colour bands blue, orange, orange. What is its value (in ohms)?
36. 36.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
39. 39.🧮 A 12 V battery is joined to 2 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
40. 40.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =

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