Assertion (A): The resistance of a copper specimen changes by about 22% when tem

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Question
Assertion (A): The resistance of a copper specimen changes by about 22% when temperature is increased from room temperature to 700�C.
Reason (R): The physical properties of a material are determined mostly by the extent of impurities.
Options
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true but R is false
D. A is false but R is true

Correct Answer

Both A and R are true but R is not correct explanation of A

Explanation

The increase of resistance with temperature is governed by temperature coefficient of resistance.

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2. If q is charge on an electron, R is radius of electron orbit and ? is angular velocity of electron rotation, the magnetic dipole moment of electron in orbit is
Options
A. 0.5 q?R
B. 0.5 q²?²R²
C. 0.5 q?R²
D. 0.5 q?²R

3. For a photoconductor with equal electron and hole mobilities and perfect ohmic contacts at the ends, an increase in intensity of optical illumination results in
Options
A. a change in o.c voltage
B. a change in s.c current
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D. increase in resistance

4. The temperature below which certain materials are antiferromagnetic and above which they are paramagnetic is called
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A. Weiss temperature
B. Curie temperature
C. Neel temperature
D. None of the above

7. Assertion (A): The optical dielectric constant (i.e., ?_r at optical frequencies)of ionic dielectrics is less than static dielectric constant.
Reason (R): At optical frequencies, P_i = 0.
Options
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true but R is false
D. A is false but R is true

8. Assertion (A): The gate current of an SCR is always in the form of pulses.
Reason (R): The gate losses, in pulse triggering, are low.
Options
A. Both A and R are correct and R is correct explanation of A
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C. A is correct but R is wrong
D. A is wrong but R is correct

9. A conductor carries 10 A current in + x direction and is lying in a field having a flux density 0.2 T directed along + z direction. The magnitude of force per metre length and direction are
Options
A. 2 N, + y direction
B. 2 N, - y direction
C. 0.02 N, + y direction
D. 0.02 N, - y direction

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