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Question

Answer 1

Step 1:

1.3.1).

Length of the aluminium conductor is 1 km=1000 m.

The diameter of the aluminum wire is d₁= 3 mm.

Since the length are same, the length of the copper wire is 1 km.

Specific resistivity of the aluminum is .

Specific resistivity of the copper .

Total current in the circuit is i_t = 350 A.

Current through copper wire is i₂ = 150 A.

The aluminum wire and copper wire are connected in parallel.

Total Current = i₁ + i₂ .

350 = i₁ + 150

i₁  =350 - 150

i₁ = 200 A.

Current through aluminum wire is  i₁ = 200 A.

Step 2:

Law of Resistivity:

Resistance offered by a conductor is given by .

Resistance offered by aluminum wire is .

Area of the aluminum wire is  .

Resistance offered by aluminum wire is .

Resistance offered by copper wire is .

Area of the copper wire is .

Resistance offered by copper wire is .

Ratio of the resistance is

Comments

Continued.....

Step 3:

In a parallel combination, the voltage across the element are same.

Substitute in equation (1).

Substitute the corresponding values in the above formula.

The diameter of the copper wire is 2.024 mm.

Solution:

The diameter of the copper wire is 2.024 mm.

Answer 2

Step 1:

(1.3.2)

Specific resistivity of the aluminum .

Specific resistivity of the copper .

Voltage drop across the aluminum is .

Current through aluminum wire is  i₁ = 200 A.

The diameter of the aluminum wire is d₁ = 3 mm.

Resistance offered by aluminum wire is .

Resistance offered by aluminum is .

Voltage drop across the aluminum:

Voltage drop across the aluminum is 792.2 v.

In a parallel combination, the voltage across both the elements are same.

Voltage drop across the copper is also 792.2 v.

Solution:

Voltage drop across the conductors is 792.2 v.

Answer 3

1.4)

Step 1:

A coil has a resistance 300 ohms at C.

Here, ohms and C.

Temperature coefficient of the resistance C .

Thus, C.

Find increase in the resistance of the coil, if the motor reaches C.

C.

Substitute corresponding values in the above expression.

Increased resistance is 12 ohms.

Solution:

Increased resistance is 12 ohms.