Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 350 · 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.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
2. 2.🧾 A family uses 50 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
3. 3.📏 How many ohms (Ω) is 2.4 kΩ?
4. 4.What does a resistor do? (a) blows if current is high (b) limits the current (c) is a resistance knob (d) makes things spin
5. 5.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
6. 6.What does a fuse do? (a) senses how hot it is (b) limits the current (c) stores a little charge (d) blows if current is high
7. 7.What does an LED do? (a) stores a little charge (b) has coloured bands (c) blows if current is high (d) glows using little power
8. 8.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🌈 In the resistor colour code, which number does yellow stand for?
10. 10.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
11. 11.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one
12. 12.📏 How many ohms (Ω) is 1.3 kΩ?
13. 13.🧮 Resistors of 470 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
14. 14.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it lights brighter (d) it does not light
15. 15.🧩 Which component boosts a small signal? (a) diode (b) transistor (c) resistor (d) potentiometer
16. 16.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
17. 17.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
18. 18.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
19. 19.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a motor (d) a fuse
20. 20.True or false: the ammeter measures voltage. (a) False (b) True
21. 21.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
22. 22.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
23. 23.💡 An LED is joined to a 3 V battery through a 330 Ω 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
24. 24.🧮 Resistors of 10 Ω, 50 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
25. 25.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
26. 26.🧾 A 250 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
27. 27.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V × I (d) R = V ÷ I
28. 28.🔍 Which is the odd one out? (a) unplug idle chargers (b) run fans in empty rooms (c) use daylight to read (d) close the fridge quickly
29. 29.🌈 In the resistor colour code, which number does red stand for?
30. 30.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
31. 31.True or false: how much a part resists is measured in volts (V). (a) False (b) True
32. 32.🔺 A current of 2 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
33. 33.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
34. 34.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I + R (d) V = I ÷ R
35. 35.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
36. 36.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
37. 37.🧮 A 4.5 V battery is joined to 6 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
38. 38.🔺 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
39. 39.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
40. 40.🧮 A 0.7 V battery is joined to 5 Ω and 2 Ω resistors in series. What current flows (in amperes)? =

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