Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 94 · 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.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
2. 2.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
4. 4.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
5. 5.Which of these is measured in amperes (A)? (a) current (b) power (c) resistance (d) voltage
6. 6.🌈 In the resistor colour code, which number does red stand for?
7. 7.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the pipe colour (c) the flow of water (d) a narrow pipe
8. 8.🧾 A 1000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
9. 9.🌈 In the resistor colour code, which number does yellow stand for?
10. 10.🧮 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
11. 11.🧾 A 50 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
12. 12.Which of these is measured in ohms (Ω)? (a) voltage (b) power (c) resistance (d) energy used each second
13. 13.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 24000 Ω resistor? (a) red-yellow-orange (b) red-yellow-red (c) yellow-red-orange (d) red-yellow-yellow
15. 15.True or false: voltage is measured in volts (V). (a) False (b) True
16. 16.🌈 A resistor has the colour bands white, brown, orange. What is its value (in ohms)?
17. 17.🧩 Which component makes things spin? (a) diode (b) capacitor (c) motor (d) thermistor
18. 18.🌈 A resistor has the colour bands red, red, red. What is its value in kilo-ohms (kΩ)? =
19. 19.🔍 Which is the odd one out? (a) leave the TV on standby (b) close the fridge quickly (c) unplug idle chargers (d) use LED lamps
20. 20.🧾 A 1000 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
21. 21.True or false: a motor turns a fan or wheels. (a) False (b) True
22. 22.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
23. 23.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
24. 24.🔺 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
25. 25.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
26. 26.🌈 A resistor has the colour bands brown, orange, red. What is its value in kilo-ohms (kΩ)? =
27. 27.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a fuse (d) a motor
28. 28.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
29. 29.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
30. 30.🌈 A resistor has the colour bands brown, blue, yellow. What is its value in kilo-ohms (kΩ)? =
31. 31.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) low energy device (d) light energy dial
32. 32.True or false: to unplug idle chargers wastes electricity. (a) True (b) False
33. 33.🧩 Which component is a resistance knob? (a) LED (b) diode (c) potentiometer (d) capacitor
34. 34.📏 How many amperes (A) is 110 mA? =
35. 35.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
36. 36.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
37. 37.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
38. 38.💡 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) lights up (b) does not light (c) may burn out
39. 39.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water tank lid (c) the water pressure (d) the pipe colour
40. 40.🔺 A 12 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =

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