Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 550 · 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 current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a motor (c) an LED (d) a fuse
3. 3.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
4. 4.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 23000 Ω resistor? (a) red-orange-yellow (b) red-orange-red (c) red-orange-orange (d) orange-red-orange
6. 6.🔺 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
7. 7.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
8. 8.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the water pressure (c) the tap handle (d) the pipe colour
9. 9.True or false: current is measured in watts (W). (a) True (b) False
10. 10.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
11. 11.🌈 A resistor has the colour bands white, orange, yellow. What is its value in kilo-ohms (kΩ)? =
12. 12.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
13. 13.True or false: a thermistor senses how hot it is. (a) False (b) True
14. 14.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) energy used each second (c) current (d) voltage
15. 15.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
16. 16.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
17. 17.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 ampere
18. 18.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
19. 19.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V + R (d) I = V × R
21. 21.📏 How many ohms (Ω) is 1.5 kΩ?
22. 22.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
24. 24.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
25. 25.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
26. 26.🌈 A resistor has the colour bands yellow, green, yellow. What is its value in kilo-ohms (kΩ)? =
27. 27.📏 How many ohms (Ω) is 4.5 kΩ?
28. 28.⚡ A 3 W device works on 3 V. What current does it take (in amperes)? =
29. 29.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
30. 30.🧮 Resistors of 47 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
31. 31.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
32. 32.🔺 A current of 2.5 A flows when 37.5 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
34. 34.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
35. 35.🧮 Resistors of 47 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
36. 36.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the gold band (d) the one nearest an end
37. 37.🔺 A current of 0.2 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.Which of these is measured in watts (W)? (a) the push of a cell (b) how much a part resists (c) the flow of charge (d) power
39. 39.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) a filament bulb (d) an LED lamp

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