Simple circuits

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Question 12
Medium

A student makes a circuit using a cell, three switches, and two identical filament lamps, as shown in the diagram.

A circuit diagram with a cell at the top. The positive terminal of the cell is on the left. A wire goes down from the left side to a single-pole switch labeled S_1. After this switch, the wire splits into two parallel branches. The top parallel branch contains a switch S_2 in series with a lamp labeled L_1. The bottom parallel branch contains a switch S_3 in series with a lamp labeled L_2. On the right, the two parallel branches recombine into a single wire that connects back to the negative terminal of the cell.

a.

Which switch or switches does the student close so that only lamp L1L_1L1​ lights up?

[1]
b.

Which switch or switches does the student close so that only lamp L2L_2L2​ lights up?

[1]
c.

The switches are closed so that both lamp L1L_1L1​ and lamp L2L_2L2​ light up.

Which sentence describes the brightness of lamp L1L_1L1​ and lamp L2L_2L2​?

  • Both lamps are the same brightness.
  • Lamp L1L_1L1​ is brighter than lamp L2L_2L2​.
  • Lamp L2L_2L2​ is brighter than lamp L1L_1L1​.
[1]
d.

Explain your answer to (c).

[2]
e.

Complete the sentences to explain what happens to the metal wire inside the filament lamp when the current increases. Use words from the list below:

  • atoms
  • decreases
  • electrons
  • increases
  • ions
  • protons
  • thermal
  • vibrate

As the current increases, the moving free .................... collide more frequently with the positive .................... in the metal lattice. This lattice disturbance .................... the overall resistance of the wire.

[2]

Simple circuits Questions

  1. GCSE
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