Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 103 · 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.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) a bigger tank (c) a narrow pipe (d) the flow of water
2. 2.🌈 A resistor has the colour bands brown, red, red. What is its value in kilo-ohms (kΩ)? =
3. 3.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V + R (c) I = V × R (d) I = R ÷ V
4. 4.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
5. 5.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
7. 7.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🔍 Which is the odd one out? (a) use old filament bulbs (b) close the fridge quickly (c) use LED lamps (d) use daylight to read
9. 9.📏 Which unit measures how much a part resists? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
10. 10.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) a filament bulb (d) an LED lamp
11. 11.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
12. 12.🌈 A resistor has the colour bands green, yellow, red. What is its value in kilo-ohms (kΩ)? =
13. 13.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) an LED (d) a resistor
14. 14.⚡ A device works on 9 V and takes 0.25 A. What is its power (in watts)? =
15. 15.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
16. 16.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %
17. 17.🧩 Which component is a resistance knob? (a) potentiometer (b) LDR (c) fuse (d) resistor
18. 18.🧮 Resistors of 47 Ω, 47 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
19. 19.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
20. 20.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
21. 21.📏 How many watts (W) is 4.5 kW?
22. 22.🧩 Which component boosts a small signal? (a) diode (b) potentiometer (c) transistor (d) thermistor
23. 23.🌈 A resistor has the colour bands yellow, grey, yellow. What is its value in kilo-ohms (kΩ)? =
24. 24.🌈 A resistor has the colour bands white, white, yellow. What is its value in kilo-ohms (kΩ)? =
25. 25.🧮 A 0.9 V battery is joined to 6 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
26. 26.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
27. 27.True or false: a motor blows if current is high. (a) False (b) True
28. 28.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) stay the same (d) bigger
29. 29.⚡ A 2.25 W device works on 1.5 V. What current does it take (in amperes)? =
30. 30.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = I × R (d) V = R ÷ I
31. 31.🧩 Which component turns a fan or wheels? (a) LED (b) transistor (c) diode (d) motor
32. 32.🔺 A current of 1.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.Which of these is measured in volts (V)? (a) energy used each second (b) current (c) how much a part resists (d) the push of a cell
34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 51000 Ω resistor? (a) green-brown-red (b) green-brown-orange (c) brown-green-orange (d) green-brown-yellow
35. 35.🧾 A 250 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
36. 36.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
37. 37.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
38. 38.⚡ A device works on 24 V and takes 1.5 A. What is its power (in watts)? =
39. 39.🔺 A current of 0.1 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
40. 40.🧩 Which component glows using little power? (a) buzzer (b) transistor (c) resistor (d) LED

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