Two conductors made of the same material are connected across the same potential difference. Conductor A has twice the diameter and twice the length of conductor B. What is the ratio of the power delivered to A to the power delivered to B?

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**Problem Statement:**

Two conductors made of the same material are connected across the same potential difference. Conductor A has twice the diameter and twice the length of conductor B. What is the ratio of the power delivered to A to the power delivered to B?

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**Solution Explanation:**

When two conductors are made from the same material, they have the same resistivity. The resistance \( R \) of a conductor can be calculated using the formula:

\[ R = \frac{\rho L}{A} \]

where \( \rho \) is the resistivity, \( L \) is the length, and \( A \) is the cross-sectional area. 

Since Conductor A has twice the diameter of Conductor B, its radius is also twice, and therefore, its cross-sectional area is four times that of B because area \( A \) for a cylinder is \( \pi r^2 \). 

Given: 

- Length of A is \( 2L_B \)
- Diameter of A is \( 2d_B \) which makes its area \( 4A_B \)

Thus, the resistance of A, \( R_A \), becomes:

\[ R_A = \frac{\rho \cdot 2L_B}{4A_B} = \frac{\rho \cdot L_B}{2A_B} = \frac{1}{2}R_B \]

The power \( P \) delivered to a conductor connected across a potential difference \( V \) is given by:

\[ P = \frac{V^2}{R} \]

Therefore, the power delivered to each conductor will be:

\[ P_A = \frac{V^2}{R_A} \]
\[ P_B = \frac{V^2}{R_B} \]

Since \( R_A = \frac{1}{2}R_B \),

\[ P_A = \frac{V^2}{\frac{1}{2}R_B} = 2 \times \frac{V^2}{R_B} = 2P_B \]

**Conclusion:**

The ratio of the power delivered to A to the power delivered to B is 2:1.
Transcribed Image Text:**Problem Statement:** Two conductors made of the same material are connected across the same potential difference. Conductor A has twice the diameter and twice the length of conductor B. What is the ratio of the power delivered to A to the power delivered to B? --- **Solution Explanation:** When two conductors are made from the same material, they have the same resistivity. The resistance \( R \) of a conductor can be calculated using the formula: \[ R = \frac{\rho L}{A} \] where \( \rho \) is the resistivity, \( L \) is the length, and \( A \) is the cross-sectional area. Since Conductor A has twice the diameter of Conductor B, its radius is also twice, and therefore, its cross-sectional area is four times that of B because area \( A \) for a cylinder is \( \pi r^2 \). Given: - Length of A is \( 2L_B \) - Diameter of A is \( 2d_B \) which makes its area \( 4A_B \) Thus, the resistance of A, \( R_A \), becomes: \[ R_A = \frac{\rho \cdot 2L_B}{4A_B} = \frac{\rho \cdot L_B}{2A_B} = \frac{1}{2}R_B \] The power \( P \) delivered to a conductor connected across a potential difference \( V \) is given by: \[ P = \frac{V^2}{R} \] Therefore, the power delivered to each conductor will be: \[ P_A = \frac{V^2}{R_A} \] \[ P_B = \frac{V^2}{R_B} \] Since \( R_A = \frac{1}{2}R_B \), \[ P_A = \frac{V^2}{\frac{1}{2}R_B} = 2 \times \frac{V^2}{R_B} = 2P_B \] **Conclusion:** The ratio of the power delivered to A to the power delivered to B is 2:1.
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