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Electronics Worksheet: Simple Circuit – Open and Closed

Electronics lesson 4: Open and closed circuits · Set 346 · 40 questions
TalentJR

Remember (Follow the loop): Closed circuit = complete loop = current flows; open circuit = a break = no current. Check every part: live cell, good bulb, switch ON, all wires joined, any gap bridged by a conductor. If even one check fails, the bulb does not glow.

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  1. 1.🔁 Is the circuit closed or open if the switch is ON? (a) open (b) closed
  2. 2.🔁 Is the circuit closed or open if a cell is taken out? (a) open (b) closed
  3. 3.🔦 A circuit has a new cell, a good bulb and a switch that is ON. All the wires are firmly joined. Does the bulb glow? (a) No (b) Yes
  4. 4.🔁 In an old-style bulb, which thin wire glows when current flows? (a) the glass (b) the base (c) the switch (d) the filament
  5. 5.🔁 What do we call a circuit with a break in it? (a) a closed circuit (b) a full circuit (c) an open circuit (d) a series circuit
  6. 6.🔁 Is the circuit closed or open if the loop is complete? (a) closed (b) open
  7. 7.True or false: if the bulb is unscrewed, the circuit is closed and current flows. (a) False (b) True
  8. 8.True or false: if a cell is taken out, the circuit is open and no current flows. (a) True (b) False
  9. 9.Which of these means the circuit is open? (a) all wires are joined (b) the loop is complete (c) a wire is cut (d) the switch is ON
  10. 10.Which of these means the circuit is closed? (a) the bulb is unscrewed (b) a wire has come loose (c) a cell is taken out (d) the switch is ON
  11. 11.🔦 A circuit has a new cell, a good bulb and a switch that is ON. One wire has come loose from the cell. A gap in one wire is bridged by a wooden stick. Does the bulb glow? (a) No (b) Yes
  12. 12.🔦 A circuit has a new cell, a good bulb and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a steel spoon. Does the bulb glow? (a) Yes (b) No
  13. 13.🔦 A circuit has a new cell, a bulb with a broken filament and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a steel spoon. Does the bulb glow? (a) Yes (b) No
  14. 14.🔦 A circuit has a new cell, a good bulb and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by aluminium foil. Does the bulb glow? (a) No (b) Yes
  15. 15.🔁 Is the circuit closed or open if a wire is cut? (a) open (b) closed
  16. 16.🔦 A circuit has a new cell, a good bulb and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a plastic straw. Does the bulb glow? (a) No (b) Yes
  17. 17.🔦 A circuit has a used-up (dead) cell, a good bulb and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a rubber eraser. Does the bulb glow? (a) No (b) Yes
  18. 18.🔦 A circuit has a new cell, a good bulb and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a copper wire. Does the bulb glow? (a) No (b) Yes
  19. 19.🔁 Is the circuit closed or open if the switch is OFF? (a) closed (b) open
  20. 20.🔦 A circuit has a used-up (dead) cell, a good bulb and a switch that is ON. All the wires are firmly joined. Does the bulb glow? (a) Yes (b) No
  21. 21.True or false: if all wires are joined, the circuit is open and no current flows. (a) True (b) False
  22. 22.True or false: if the switch is OFF, the circuit is open and no current flows. (a) True (b) False
  23. 23.🔦 A circuit has a new cell, a good bulb and a switch that is OFF. All the wires are firmly joined. A gap in one wire is bridged by a woollen thread. Does the bulb glow? (a) No (b) Yes
  24. 24.True or false: if the bulb is unscrewed, the circuit is open and no current flows. (a) False (b) True
  25. 25.🔦 A circuit has a new cell, a bulb with a broken filament and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a wooden stick. Does the bulb glow? (a) No (b) Yes
  26. 26.🔦 A circuit has a new cell, a good bulb and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a woollen thread. Does the bulb glow? (a) No (b) Yes
  27. 27.Which of these means the circuit is closed? (a) a cell is taken out (b) a wire is cut (c) the bulb is unscrewed (d) all wires are joined
  28. 28.True or false: if the switch is OFF, the circuit is closed and current flows. (a) False (b) True
  29. 29.🔦 A circuit has a new cell, a good bulb and a switch that is OFF. All the wires are firmly joined. A gap in one wire is bridged by a steel spoon. Does the bulb glow? (a) Yes (b) No
  30. 30.🔦 A circuit has a new cell, a bulb with a broken filament and a switch that is ON. All the wires are firmly joined. Does the bulb glow? (a) Yes (b) No
  31. 31.🔁 A bulb has two contacts. How many must be joined into the loop for it to glow? (a) none (b) it does not matter (c) only one (d) both of them
  32. 32.🔦 A circuit has a new cell, a good bulb and a switch that is ON. One wire has come loose from the cell. A gap in one wire is bridged by a safety pin. Does the bulb glow? (a) Yes (b) No
  33. 33.🔁 Is the circuit closed or open if a wire has come loose? (a) closed (b) open
  34. 34.🔦 A circuit has a new cell, a good bulb and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a metal paper clip. Does the bulb glow? (a) Yes (b) No
  35. 35.🔦 A circuit has a new cell, a good bulb and a switch that is ON. One wire has come loose from the cell. A gap in one wire is bridged by a brass key. Does the bulb glow? (a) Yes (b) No
  36. 36.Which of these means the circuit is open? (a) the switch is ON (b) the loop is complete (c) a cell is taken out (d) all wires are joined
  37. 37.Which of these means the circuit is closed? (a) the bulb is unscrewed (b) a wire has come loose (c) a cell is taken out (d) the loop is complete
  38. 38.True or false: if a wire is cut, the circuit is open and no current flows. (a) False (b) True
  39. 39.Which of these means the circuit is open? (a) the loop is complete (b) all wires are joined (c) the switch is ON (d) the bulb is unscrewed
  40. 40.🔁 What must there be for a current to flow? (a) a plastic gap (b) a broken path (c) a complete loop (d) one loose end

Answer key

  1. closed
  2. open
  3. Yes
  4. the filament
  5. an open circuit
  6. closed
  7. False
  8. True
  9. a wire is cut
  10. the switch is ON
  11. No
  12. Yes
  13. No
  14. Yes
  15. open
  16. No
  17. No
  18. Yes
  19. open
  20. No
  21. False
  22. True
  23. No
  24. True
  25. No
  26. No
  27. all wires are joined
  28. False
  29. No
  30. No
  31. both of them
  32. No
  33. open
  34. Yes
  35. No
  36. a cell is taken out
  37. the loop is complete
  38. True
  39. the bulb is unscrewed
  40. a complete loop

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