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  • Please help! A piece of copper and another of germanium are cooled from room temperature to 77 K, the resistance of

A piece of copper and another of germanium are cooled from room temperature to 77 K, the resistance of

  • Option 1)

    each of them increases

  • Option 2)

    each of them decreases

  • Option 3)

    copper decreases and germanium increases

  • Option 4)

    copper increases and germanium decreases.

 

Answers (1)

As we learnt in

Number of electrons or holes -

n_{e}= n_{\lambda }= AT^{3/2}e^{-Eg /2KT}
 

- wherein

Eg = Energy gap

K = Boltzmann Constant

T = Temperature in kelvin

On increasing temperature,  the number of current carried increases

 

 As temperature is decreased.

1.    Resistance of conductor decreases.

2.    Resistance of semiconductor increases.

Since Cu is conductor its resistance decreases and resistance of germanium (semiconductor) increases here. 

Correct option is 3.

 


Option 1)

each of them increases

This is an incorrect option.

Option 2)

each of them decreases

This is an incorrect option.

Option 3)

copper decreases and germanium increases

This is the correct option.

Option 4)

copper increases and germanium decreases.

This is an incorrect option.

Posted by

Vakul

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