Question

A student constructs four electric circuits.

Each circuit includes two bulbs and an ammeter.
All the bulbs, all the cells and all the ammeters are identical.
The ammeter readings for the first two circuits are shown.
Use values from the box to complete the ammeter readings for the other two circuits.

Answer 1

Part A

The ammeter reading for the current flowing through the second bulb, in the third circuit is 0.43 A

Part B

The ammeter reading for the total current coming from the cell is 0.86 A

Step-by-step explanation:

The given electric circuit schematics includes;

The number of bulbs in each circuit = 2 bulbs

The number of ammeter in each circuit = 1 ammeter

The number of cells in each circuit = 1

Each circuit have identical bulbs, cells and ammeters

Part A

Ammeter reading for the third circuit

The given reading for the total current going to the cell,
`I_T` = 0.86 A

The reading for the current flowing through one of the bulbs, I₁ = 0.43 A

Therefore, given that the bulbs are arranged in parallel, and the bulbs have identical resistance, 'R', the current flowing in the second bulb, I₂, is given by the current divider rule as follows;

`I_2 = (R)/(R + R) * I_T = (R)/(2 \cdot R) * I_T = (1)/(2) * I_T`

∴ The ammeter reading for the current flowing through the second bulb, in the third circuit I₂ = (1/2) × (0.86 A) = 0.43 A

Part B

Ammeter reading for the third circuit

The total current coming from the cell = The current passing through the bulbs = I₁ + I₂

The ammeter reading for the total current coming from the cell = 0.43 A + 0.43 A = 0.86 A =
`I_T`