Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 424 · 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.🧮 Resistors of 33 Ω, 330 Ω, 22 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
2. 2.True or false: current is measured in amperes (A). (a) False (b) True
3. 3.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) smaller (d) zero
4. 4.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 watt
5. 5.What does a motor do? (a) boosts a small signal (b) is a resistance knob (c) senses how bright it is (d) turns a fan or wheels
6. 6.🔺 A current of 1 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.True or false: a potentiometer smooths a wobbly supply. (a) False (b) True
8. 8.🔺 A current of 0.1 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
9. 9.🔺 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
10. 10.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
11. 11.What does a diode do? (a) boosts a small signal (b) makes a beeping sound (c) lets current go one way (d) glows using little power
12. 12.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
13. 13.🌈 A resistor has the colour bands green, black, red. What is its value in kilo-ohms (kΩ)? =
14. 14.🧩 Which component beeps for an alarm? (a) buzzer (b) capacitor (c) thermistor (d) resistor
15. 15.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
16. 16.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
17. 17.🧩 Which component glows using little power? (a) LED (b) potentiometer (c) motor (d) capacitor
18. 18.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) measure heat (d) store charge briefly
19. 19.⚡ A 1.8 W device works on 9 V. What current does it take (in amperes)? =
20. 20.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a diode (d) a buzzer
21. 21.🌈 A resistor has the colour bands red, black, red. What is its value (in ohms)?
22. 22.📏 How many kilowatts (kW) is 1150 W? =
23. 23.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
24. 24.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
25. 25.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
26. 26.🧮 A 2.8 V battery is joined to 12 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
27. 27.📏 How many kilo-ohms (kΩ) is 9200 Ω? =
28. 28.True or false: energy used each second is measured in ohms (Ω). (a) True (b) False
29. 29.🔺 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
30. 30.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
31. 31.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
32. 32.🔺 A current of 2 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) less than either one (d) always zero
34. 34.🧮 A 3.5 V battery is joined to 6 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
35. 35.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
36. 36.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
37. 37.💡 An LED is joined to a 9 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
38. 38.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.🌈 A resistor has the colour bands violet, brown, red. What is its value in kilo-ohms (kΩ)? =
40. 40.True or false: the voltmeter is joined across a part. (a) False (b) True

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