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Topic Question Set

Q 1 :    

The resistance of platinum wire at 0°C is 2Ω and 6.8Ω at 80°C. The temperature coefficient of resistance of the wire is              [2023]
 

  • 3×10-2C∘-1

     

  • 3×10-1C∘-1

     

  • 3×10-4C∘-1

     

  • 3×10-3C∘-1

     

(1)

Given, R0=2Ω at T1=0°C and R=6.8Ω at T2=80°C

As, R=R0[1+α(T2-T1)]

6.8=2[1+α(80-0)]⇒6.8=2+160α

α=0.03 or 3×10-2 °C-1

Q 2 :    

As the temperature increases, the electrical resistance                  [2022]

  • increase for both conductors and semiconductors

     

  • decreases for both conductors and semiconductors

     

  • increases for conductors but decrease for semiconductors

     

  • decreases for conductors but increases for semiconductors

     

(3)

The temperature coefficient of resistance (α) is positive for conductors and negative for insulators.

So, as the temperature increases, the resistance of conductor increases and for semiconductors decreases.

Q 3 :    

Which of the following graph represents the variation of resistivity (ρ) with temperature (T) for copper?       [2020]

  • [IMAGE 167]

     

  • [IMAGE 168]

     

  • [IMAGE 169]

     

  • [IMAGE 170]

     

(3)

For metals, resistivity versus time graph is

[IMAGE 171]

 

Q 4 :    

The solids which have the negative temperature coefficient of resistance are                [2020]

  • metals

     

  • insulators only

     

  • semiconductors only

     

  • insulators and semiconductors

     

(4)