Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 740 · 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.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
2. 2.📏 Which unit measures voltage? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
3. 3.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
4. 4.⚡ A 1.2 W device works on 6 V. What current does it take (in amperes)? =
5. 5.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.⚡ A 1.5 W device works on 1.5 V. What current does it take (in amperes)? =
7. 7.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
8. 8.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
9. 9.📏 How many milliamperes (mA) is 1.55 A?
10. 10.📏 How many milliamperes (mA) is 1.93 A?
11. 11.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) voltage (c) energy used each second (d) how much a part resists
12. 12.🔺 A 45 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
13. 13.🌈 A resistor has the colour bands red, brown, brown. What is its value (in ohms)?
14. 14.🧮 A 6 V battery is joined to 8 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
15. 15.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) a narrow pipe (c) the water pressure (d) the pipe colour
16. 16.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
17. 17.💡 A red LED uses 2 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
18. 18.Which of these wastes electricity? (a) use LED lamps (b) leave the TV on standby (c) set the AC to 24 °C (d) use daylight to read
19. 19.💡 A red LED uses 2 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
20. 20.🧮 Resistors of 470 Ω, 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
21. 21.True or false: resistance is measured in watts (W). (a) False (b) True
22. 22.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) less than either one (d) their sum
23. 23.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
24. 24.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
25. 25.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to change its colour (d) to make it brighter
26. 26.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a diode (d) a buzzer
27. 27.🧩 Which component senses how bright it is? (a) motor (b) resistor (c) buzzer (d) LDR
28. 28.🧮 Resistors of 10 Ω, 470 Ω, 10 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
29. 29.🌈 A resistor has the colour bands red, orange, orange. What is its value in kilo-ohms (kΩ)? =
30. 30.What does a buzzer do? (a) glows using little power (b) turns a fan or wheels (c) stores a little charge (d) makes a beeping sound
31. 31.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
32. 32.🌈 A resistor has the colour bands brown, grey, red. What is its value in kilo-ohms (kΩ)? =
33. 33.🧾 A family uses 70 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3900 Ω resistor? (a) orange-white-orange (b) orange-white-brown (c) orange-white-red (d) white-orange-red
35. 35.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
36. 36.Which of these saves electricity? (a) run fans in empty rooms (b) leave fridge door open (c) use daylight to read (d) use old filament bulbs
37. 37.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
38. 38.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
39. 39.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = I ÷ V (d) R = V + I
40. 40.🌈 A resistor has the colour bands orange, grey, orange. What is its value in kilo-ohms (kΩ)? =

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