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The resistance of a wire of 100 cmlength...

The resistance of a wire of 100 cmlength is `10Omega`. Now, it is cut into 10 equal parts and all of them are twisted to form a single bundle. Its resistances is

A

`1Omega`

B

`0.5Omega`

C

`5Omega`

D

`0.1Omega`

Text Solution

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The correct Answer is:
To solve the problem, we need to find the resistance of a wire after it has been cut into 10 equal parts and then twisted together to form a single bundle. ### Step-by-Step Solution: 1. **Identify the Initial Resistance and Length**: - The initial resistance \( R \) of the wire is given as \( 10 \, \Omega \). - The length \( L \) of the wire is \( 100 \, \text{cm} \). 2. **Cut the Wire into Equal Parts**: - The wire is cut into 10 equal parts. - Therefore, the length of each part \( L' \) will be: \[ L' = \frac{L}{10} = \frac{100 \, \text{cm}}{10} = 10 \, \text{cm} \] 3. **Calculate the Resistance of Each Part**: - The resistance of a wire is given by the formula: \[ R = \rho \frac{L}{A} \] where \( \rho \) is the resistivity, \( L \) is the length, and \( A \) is the cross-sectional area. - When the wire is cut into 10 parts, the resistance of each part \( R' \) can be calculated as: \[ R' = \frac{R}{n} = \frac{10 \, \Omega}{10} = 1 \, \Omega \] - Here, \( n \) is the number of parts (which is 10). 4. **Combine the Resistors in Parallel**: - When all 10 parts are twisted together, they are effectively connected in parallel. - The equivalent resistance \( R_{eq} \) of resistors in parallel is given by: \[ \frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \ldots + \frac{1}{R_n} \] - Since all resistances are equal: \[ \frac{1}{R_{eq}} = \frac{10}{R'} = \frac{10}{1 \, \Omega} = 10 \] - Therefore, the equivalent resistance \( R_{eq} \) is: \[ R_{eq} = \frac{1}{10} = 0.1 \, \Omega \] 5. **Final Answer**: - The resistance of the twisted bundle of wires is \( 0.1 \, \Omega \).

To solve the problem, we need to find the resistance of a wire after it has been cut into 10 equal parts and then twisted together to form a single bundle. ### Step-by-Step Solution: 1. **Identify the Initial Resistance and Length**: - The initial resistance \( R \) of the wire is given as \( 10 \, \Omega \). - The length \( L \) of the wire is \( 100 \, \text{cm} \). ...
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