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A copper rod of 1 cm diameter and 8 cm length is drawn into a wire of uniform diameter and 18 m length. The radius (in cm) of the wire is
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- 1/15
- 1/30
- 2/15
- 15
- 1/15
Correct Option: B
Let the radius of wire = r cm.
| Volume of copper rod = π × |  |  | ² | × 8 = 2πcm³ | |
| 2 |
Volume of wire = πr² × 1800
= 1800 πr² cm³
Clearly,
1800 πr² = 2π
| ⇒ r² = | ⇒ r = | ||
| 900 | 3 |
