Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 727 · 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.What does a diode do? (a) senses how hot it is (b) lets current go one way (c) smooths a wobbly supply (d) makes a beeping sound
2. 2.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it does not light (d) it makes a sound
3. 3.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 1000 (c) 10 (d) 60
4. 4.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
5. 5.Which of these is measured in watts (W)? (a) resistance (b) power (c) the push of a cell (d) how much a part resists
6. 6.🔺 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
7. 7.True or false: energy used each second is measured in amperes (A). (a) True (b) False
8. 8.True or false: the voltmeter measures voltage. (a) False (b) True
9. 9.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
10. 10.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
11. 11.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
12. 12.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
13. 13.🌈 A resistor has the colour bands brown, orange, yellow. What is its value in kilo-ohms (kΩ)? =
14. 14.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the length of a wire (d) the size of a cell
15. 15.⚡ A device works on 12 V and takes 0.5 A. What is its power (in watts)? =
16. 16.Which of these wastes electricity? (a) close the fridge quickly (b) switch off empty rooms (c) use LED lamps (d) iron one shirt at a time
17. 17.🔺 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
18. 18.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
19. 19.True or false: a motor makes things spin. (a) False (b) True
20. 20.🔺 A 25 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
21. 21.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
22. 22.What does a motor do? (a) stores a little charge (b) is a resistance knob (c) makes things spin (d) makes a beeping sound
23. 23.⚡ A device works on 1.5 V and takes 2 A. What is its power (in watts)? =
24. 24.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
25. 25.🔺 A current of 2.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
26. 26.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
27. 27.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 6.5 V supply. What current flows (in mA)?
28. 28.🧩 Which part changes electrical energy into movement? (a) a motor (b) a resistor (c) a fuse (d) an LED
29. 29.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) low energy device (d) light energy dial
30. 30.📏 How many ohms (Ω) is 0.8 kΩ?
31. 31.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
32. 32.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 350 Ω resistor? (a) orange-green-red (b) orange-green-brown (c) orange-green-black (d) green-orange-brown
34. 34.True or false: a diode blows if current is high. (a) False (b) True
35. 35.🧮 A 100 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
36. 36.📏 How many milliamperes (mA) is 2.54 A?
37. 37.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I + R (c) V = R ÷ I (d) V = I ÷ R
38. 38.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 4.25 V supply. What current flows (in mA)?
39. 39.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
40. 40.True or false: the ammeter measures current. (a) False (b) True

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