Home
Class 12
PHYSICS
A copper wire having cross- sectional ar...

A copper wire having cross- sectional area of `0.5 mm^2` and a length of ` 0.1 m` is initially at `25^@C` and is thermally insulated form the surrounding. If a current of `10A` is set up in this wire, (a) find the time in which the wire will start melting. (b) What will be the change of resistance with time, if the length of the wire is doubled? For copper, resistivity is `1.6xx10^(-8)Omega m,` density is `9,000 kgm^(-3)` and specific heat capacity is `0.09 cal g^(-1)C^(-1).` Melting temperature of copper is `1075^@C`

Text Solution

Verified by Experts

`I^2Rt=ms Delta theta=m (S Delta theta), I^2(p_1 .1/A)t=A.b^2 (s Delta theta)`
Here `p_1`= specific resistance and `p_2`= density `therefore t=(A^2p_2(s Delta theta))/(I^2p_1)`………(i)
Substituting the values ,we have
`t=((0.5 times 10^-6)^2 (9 times 10^-2 times 4.19 times 1050))/((10)^2(1.6 times 10^-8))=55.5s`
Promotional Banner

Similar Questions

Explore conceptually related problems

A copper wire having cross- sectional area of 0.5 mm^2 and a lentgth of 0.1 m is initially at 25^@C and is thermally insulated form the surronding. If a current of 10A is set up in this wire, (a) find the time in which the wire will start melting. The change of resistance with time be, if the length of the wire is doubled? For copper, resistivity is 1.6xx10^(-8)Omega m, density is 9,000 kgm^(-3) and specific heat capacity is 0.09 cal g^(-10)C^(-1). Melting temperature fo copper is 1075^@C

A copper wire having cross-sectional area 0.5mm^(2) and a length 0.1 m is initially at 25^(@)C and is thennallyinsulated from the surrounding. If a current of 10 A is set up in this wire, (a) Find the time in which the wire will start melting. The change ofresistancewith the temperature of the wire maybe neglected. (b) What will be the time taken iflength of the wire is doubled? Given for copper wire, its density 9xx10^(3) kg//^(3) specific heat 9xx10^(-2) kcal//kg .^(@)C melting point 1075^(@)C and specific resistance 1.6 xx 10^(-8) Omega-m

A copper wire having area of cross section 0.4mm^(2) and a length of 10 cm is initially at 75^(@)C and is thermally insulated from the surroundings. If a current of 10A is set up in this wire. ltbr. (a) Find the time in which the wire will strat melting. ignore variation of resistance with temperature. (b) If length of wire is doubled, find time. Given for copper : density = 10^(4) kg//m^(3) , specific heat = 9xx10^(-2) kcal kg^(-1)(.^@C)^(-1) , melting point = 1075^(@)C , resispectively =1.6xx10^(-8)Omega * m .

The resistance of a wire of length 330m and cross-section area 1.0 mm^(2) made of material of resistivity 1.0 xx 10^(-7) Omegam is:

What is the length of a wire of radius 0.2 mm and resitance 25 Omega ? The restivity of the material of the wire is 2pi xx 10^(-8) Omega.m.

A copper wire has a square cross section of 6 mm on a side. The wire is 10 m long and carries a current of 3.6A. The density of free electrons id 8.5x10^(28)//m^3. Find the magnitude of (a) the current density in the wire , (b) the electric field in the wire. (c ) How much time is required for an electron to travel the length of the wire? ("rh, electrical resistivity, is" 1.72 xx10^(-8) Omegam.)

When the resistance of copper wire is 0.1 Omega and the radius is 1mm, then the length of the wire is (specific resistance of copper is 3.14 xx 10^(-8) ohm xx m )