Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 590 · 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 0.6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
2. 2.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
3. 3.🌈 A resistor has the colour bands red, green, red. What is its value (in ohms)?
4. 4.🧮 A 22 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
5. 5.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
6. 6.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
7. 7.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
8. 8.🧮 Resistors of 68 Ω, 10 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
9. 9.📏 How many amperes (A) is 420 mA? =
10. 10.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
11. 11.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🔺 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
13. 13.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
14. 14.🔺 A current of 25 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
15. 15.🧮 Resistors of 33 Ω, 220 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
16. 16.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
17. 17.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
18. 18.True or false: an LDR senses how bright it is. (a) True (b) False
19. 19.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
20. 20.🧾 A family uses 190 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
21. 21.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) stay the same (d) smaller
22. 22.Which of these is measured in volts (V)? (a) the flow of charge (b) how much a part resists (c) current (d) voltage
23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 28 Ω resistor? (a) red-grey-black (b) red-grey-brown (c) orange-grey-black (d) grey-red-black
24. 24.🔺 A 4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
25. 25.💡 An LED is joined to a 6 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
26. 26.Which of these saves electricity? (a) use daylight to read (b) run fans in empty rooms (c) leave fridge door open (d) use old filament bulbs
27. 27.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it lights brighter (d) it does not light
28. 28.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
29. 29.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
30. 30.Which of these saves electricity? (a) iron one shirt at a time (b) leave the TV on standby (c) leave fridge door open (d) switch off empty rooms
31. 31.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) less than either one (d) always zero
32. 32.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
33. 33.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
34. 34.📏 Which unit measures how much a part resists? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
35. 35.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
36. 36.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
37. 37.🧮 A 1.2 V battery is joined to 8 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
38. 38.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1024 (c) 1000 (d) 10
40. 40.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)

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