Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 220 · 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.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
2. 2.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) energy used each second (d) the length of a wire
3. 3.Which of these is measured in amperes (A)? (a) power (b) the flow of charge (c) voltage (d) the push of a cell
4. 4.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
5. 5.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
7. 7.What does a capacitor do? (a) stores a little charge (b) blows if current is high (c) makes a beeping sound (d) beeps for an alarm
8. 8.True or false: a diode stores a little charge. (a) True (b) False
9. 9.📏 How many milliamperes (mA) is 2.33 A?
10. 10.True or false: the voltmeter measures current. (a) False (b) True
11. 11.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
12. 12.🔺 A current of 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
13. 13.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
14. 14.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
15. 15.🧩 Which part changes electrical energy into movement? (a) a motor (b) an LED (c) a resistor (d) a fuse
16. 16.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
17. 17.True or false: a thermistor senses how hot it is. (a) False (b) True
18. 18.🔺 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
19. 19.True or false: to set the AC to 24 °C wastes electricity. (a) False (b) True
20. 20.💡 Does it save or waste electricity to leave fridge door open? (a) wastes electricity (b) saves electricity
21. 21.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
22. 22.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) becomes zero (d) gets smaller
23. 23.Which of these is measured in watts (W)? (a) the push of a cell (b) current (c) power (d) the flow of charge
24. 24.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
26. 26.📏 How many milliamperes (mA) is 0.2 A?
27. 27.What does a potentiometer do? (a) stores a little charge (b) limits the current (c) blows if current is high (d) is a resistance knob
28. 28.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it does not light (c) it lights brighter (d) it makes a sound
29. 29.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 watt (d) 1 ampere
30. 30.True or false: the push of a cell is measured in watts (W). (a) True (b) False
31. 31.🌈 In the resistor colour code, which number does blue stand for?
32. 32.🧾 A 1000 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
33. 33.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) the one nearest an end (d) any band
34. 34.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
35. 35.🔺 A current of 0.2 A flows when 1 V is joined across a resistor. What is its resistance (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 home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
38. 38.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 50 % (d) 0 %
40. 40.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)

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