Science 9 · Unit 9: Electricity · Cambridge Lower Secondary Science Stage 9

Questions

1. 1. In a parallel circuit, how does the current through the cell compare with the current in each branch?

   • It equals the branch currents added together.
   • It is smaller than each branch.
   • It is the same as each branch.
   • It is zero.
   Check

2. 2. A circuit has three parallel branches with currents of 1.0 A, 2.0 A and 0.5 A. What is the current through the cell?

   • 3.5 A
   • 0.5 A
   • 2.0 A
   • 1.0 A
   Check

3. 3. The current through the cell is 5.5 A. The branches carry 3.0 A, 1.5 A and X through the buzzer. What is X?

   • 1.5 A
   • 4.5 A
   • 1.0 A
   • 10.0 A
   Check

4. 4. Four identical lamps are connected in parallel. When all four are working, the current through the cell is 2.0 A. What is the current through each lamp?

   • 0.5 A
   • 2.0 A
   • 1.0 A
   • 8.0 A
   Check

5. 5. Why are the lamps in a string of lights often connected in parallel?

   • If one lamp fails, the others still light.
   • It uses fewer wires.
   • It needs no cell.
   • It makes the lamps dimmer.
   Check

6. 6. What is a parallel circuit?

   • a circuit with more than one path (branch) for the current
   • a circuit with all the components in one loop
   • a circuit with no cell
   • a circuit with only one lamp
   Check

7. 7. Where does the current divide in a parallel circuit?

   • inside a lamp
   • it never divides
   • inside the cell
   • at a junction, where the branches split
   Check

8. 8. Each branch of a parallel circuit carries 3 A. What is the current at X, before the junction?

   • 3 A
   • 1.5 A
   • 6 A
   • 9 A
   Check

9. 9. Two identical buzzers are in parallel. The current through the cell is 4 A. What is the current through each buzzer?

   • 2 A
   • 8 A
   • 1 A
   • 4 A
   Check

10. 10. Which is a correct fact about parallel circuits?

    • Current divides between the branches.
    • There are no branches.
    • When one component fails, all stop working.
    • The current is the same everywhere.
    Check

11. 11. Which is also a correct fact about parallel circuits?

    • There are no junctions.
    • There is more than one path for the current.
    • There is only one path for the current.
    • When one component fails, all stop working.
    Check

12. 12. In a parallel circuit, one lamp breaks. What happens to the other lamps?

    • They stay on.
    • They all go out.
    • They get much dimmer.
    Check

13. 13. The circuit has two identical lamps and four ammeters. Which ammeter will show the same current as A1?

    • A4
    • A2
    • A3
    • none of them
    Check

14. 14. Which ammeter will show the same current as A2?

    • none of them
    • A1
    • A4
    • A3
    Check

15. 15. Which ammeters will show half the current shown on A4?

    • A1 only
    • A2 and A3
    • none of them
    • A1 and A2
    Check

16. 16. Which ammeters will show double the current shown on A3?

    • none of them
    • A1 and A4
    • A2 only
    • A2 and A4
    Check

17. 17. This circuit has three identical lamps and four ammeters. Which two facts are true?

    • The readings on A1, A2 and A3 must be the same, and A1 must be the largest.
    • The reading on A4 must be smaller than that on A3, and the readings on A1, A2 and A3 must be the same.
    • The reading on A1 must be the largest, and the reading on A2 must be smaller than that on A1.
    • The readings on all four ammeters must be the same.
    Check

18. 18. The reading on ammeter A3 shows the smallest current in the circuit. How do the readings on A1, A2 and A3 compare?

    • A3 is the largest, and A1 and A2 are the same.
    • A1, A2 and A3 are all the same.
    • A1 and A2 are the same, and A3 is smaller than both.
    • A1 is larger than A2, and A3 is zero.
    Check

19. 19. Which equation gives the reading on A4?

    • A4 = A1
    • A4 = A1 − A2 − A3
    • A4 = A1 × A2 × A3
    • A4 = A1 + A2 + A3
    Check

20. 20. The buzzer in the circuit stops working, so A3 now reads zero. What is the effect on the readings on A1 and A2?

    • They fall to zero.
    • They halve.
    • They stay the same.
    • They double.
    Check