Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 21 · 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 device works on 9 V and takes 0.5 A. What is its power (in watts)? =
2. 2.🔺 A 0.4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
3. 3.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
4. 4.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) their sum (d) less than either one
5. 5.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
6. 6.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V ÷ I (d) R = V + I
7. 7.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
8. 8.📏 Which unit measures energy used each second? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
9. 9.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
10. 10.🧾 A 100 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 23 Ω resistor? (a) orange-orange-black (b) red-orange-black (c) orange-red-black (d) red-orange-brown
12. 12.🧩 Which component makes things spin? (a) buzzer (b) diode (c) motor (d) LED
13. 13.📏 How many milliamperes (mA) is 0.83 A?
14. 14.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
15. 15.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
16. 16.🌈 In the resistor colour code, which number does blue stand for?
17. 17.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
18. 18.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
19. 19.📏 Which unit measures resistance? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
20. 20.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 watt
22. 22.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
23. 23.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
24. 24.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
25. 25.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
26. 26.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
27. 27.🔍 Which is the odd one out? (a) run fans in empty rooms (b) close the fridge quickly (c) leave the TV on standby (d) leave fridge door open
28. 28.🌈 A resistor has the colour bands orange, yellow, orange. What is its value (in ohms)?
29. 29.🔺 A 2 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 45000 Ω resistor? (a) yellow-green-orange (b) yellow-green-yellow (c) green-yellow-orange (d) yellow-green-red
31. 31.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
32. 32.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🧾 A family uses 160 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
34. 34.🌈 A resistor has the colour bands blue, brown, red. What is its value in kilo-ohms (kΩ)? =
35. 35.🌈 A resistor has the colour bands violet, yellow, brown. What is its value (in ohms)?
36. 36.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
37. 37.True or false: a motor turns a fan or wheels. (a) True (b) False
38. 38.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
39. 39.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) measure heat (d) spin a wheel
40. 40.Which of these wastes electricity? (a) leave the TV on standby (b) switch off empty rooms (c) use daylight to read (d) use LED lamps

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