q2 calculate the following:

Question

A battery which an emf of 8V and an internal resistance of 0.8ohms is connected across two coils in a parallel which have resistances of 10ohms and 15ohms respectively. Calculate: 1. The pd across the battery terminals 2. The current through each coil 3. The power absorbed by each coil

Answer 1

Step 1:

The emf of the battery is 8V.

The internal resistance of the battery is .

Two coils of their resistances connected in parallel.

Draw a circuit with above specifications :

 

 Step 2:

Find the equivalent resistance :

Resistor parallel.

Let is equivalent parallel resistance.

Now is in series with the internal resistance of the battery.

Answer 2

Contd.....

Step 3:

Find the current in the circuit :

From ohms law : .

Substitute .

 Step 4:

(1)

Suppose that the battery with emf  and internal resistance supplies a current  through an external load resistor , then the potential difference across the battery is .

Substitute ,  and   in .

Solution:

(1)The potential difference across battery terminal is .

Answer 3

(2)

Step 1:

The voltage in the parallel loop is .

The voltage in the parallel loop same.

So, the voltage across each coil is same.

Current through the coil which has resistance :

Use ohms law : .

Current through the coil which has resistance :

Solution:

Current through the coil is .

Current through the coil is A .
 

Answer 4

(3)

Step 1:

Power absorbed by each coil :

Power can be calculated using the relation : .

Where is power absorbed,

          is current through the coil,

          resistance of the coil.

Power absorbed by the coil is

Power absorbed by the coil is

Solution:

Power absorbed by the coil is 4.98 W.

Power absorbed by the coil is 3.32 W.