A strip of copper and another germanium are cooled from room temperature to 80 K. The resistance of

  • Option 1)

    each of these decreases

  • Option 2)

    copper strip increases and that of germanium decreases

  • Option 3)

    copper strip decreases and that of germanium increases

  • Option 4)

    each of these increases

 

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 these decreases

This is an incorrect option.

Option 2)

copper strip increases and that of germanium decreases

This is an incorrect option.

Option 3)

copper strip decreases and that of germanium increases

This is the correct option.

Option 4)

each of these increases

This is an incorrect option.

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