Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 269 · 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 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.🌈 A resistor has the colour bands violet, white, red. What is its value in kilo-ohms (kΩ)? =
3. 3.🧮 Resistors of 150 Ω, 50 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
4. 4.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
5. 5.True or false: the voltmeter measures voltage. (a) True (b) False
6. 6.True or false: a capacitor is a resistance knob. (a) True (b) False
7. 7.🔺 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
8. 8.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
9. 9.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 volt (d) 1 kilowatt-hour (kWh)
10. 10.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
11. 11.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
12. 12.🧩 Which component lets current go one way? (a) diode (b) buzzer (c) transistor (d) resistor
13. 13.🔺 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
14. 14.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = R ÷ V (d) I = V ÷ R
15. 15.⚡ An 18 W device works on 12 V. What current does it take (in amperes)? =
16. 16.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
17. 17.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
18. 18.📏 Which unit measures resistance? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
19. 19.🧮 Resistors of 33 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
20. 20.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.What does a resistor do? (a) glows using little power (b) limits the current (c) stores a little charge (d) makes things spin
22. 22.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
23. 23.🔺 A 9 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
24. 24.🔺 A current of 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
25. 25.🔺 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
26. 26.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
27. 27.💡 An LED is joined to a 9 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
28. 28.📏 How many kilo-ohms (kΩ) is 5000 Ω? =
29. 29.🌈 In the resistor colour code, which number does yellow stand for?
30. 30.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
31. 31.Which of these is measured in volts (V)? (a) current (b) resistance (c) energy used each second (d) the push of a cell
32. 32.🧮 An 8 V battery is joined to 5 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
33. 33.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
34. 34.🌈 A resistor has the colour bands red, violet, brown. What is its value (in ohms)?
35. 35.⚡ A device works on 3 V and takes 2 A. What is its power (in watts)? =
36. 36.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
37. 37.📏 Which unit measures voltage? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
38. 38.What does an LDR do? (a) makes a beeping sound (b) blows if current is high (c) senses how hot it is (d) senses how bright it is
39. 39.🔍 Which is the odd one out? (a) leave fridge door open (b) use daylight to read (c) set the AC to 24 °C (d) use LED lamps
40. 40.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =

Free electronics lessons, practice and worksheets at talentjr.in/electronics-for-kids