Physics-
General
Easy
Question
In a thin rectangular metallic strip a constant current I flows along the positive x-direction, as shown in the figure. The length, width and thickness of the strip are l, w and d, respectively. A uniform magnetic field B 
is applied on the strip along the positive y-direction. Due to this, the charge carries experience a net deflection along the z-direction. This results in accumulation of charge caries on the surface PQRS and appearance of equal and opposite charges on the face opposite to PQRS. A potential difference along the z-direction is thus developed. Charge accumulation continues until the magnetic force is balanced by the electric force. The current is assumed to be uniformly distributed on the cross section of the strip and carried by electrons.
Consider two different metallic strips (1 and 2) of the same material. Their lengths are the same, widths are 
and 
and thicknesses are 
and 
, respectively. Two points K and M are symmetrically located on the opposite faces parallel to the x-y plane (see figure). 
and 
are the potential differences between K and M in strips 1 and 2 , respectively. Then, for a given current I flowing through them in a given magnetic field strength B, the correct statement(s) is (are).
- If
and 
, then 
- If and , then
- If
and 
, then
- If and , then
and , then
and , then
and , then
and , then
The correct answer is: If and , then
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In the graphs below, the resistance R of a superconductor is shown as a function of its temperature T for two different magnetic fields 
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A superconductor has (0) = 100 K. When a magnetic field of 7.5 Tesla is applied, its decreases to 75 K. For this material one can definitely say that when
In the graphs below, the resistance R of a superconductor is shown as a function of its temperature T for two different magnetic fields (sold line) and (dashed line). If is larger than , which of the following graphs shows the correct variation of R with T in these fields? Electrical resistance of certain materials, known as superconductors, changes abruptly from a nonzero value to zero as their temperature is lowered below a critical temperature (0). An interesting property of superconductors is that their critical temperature becomes smaller than (0) if they are placed in a magnetic field, i.e., the critical temperature (B) is a function of the magnetic field strength B. The dependence of (B) on B is shown in the figure.
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In the graphs below, the resistance R of a superconductor is shown as a function of its temperature T for two different magnetic fields (sold line) and (dashed line). If is larger than , which of the following graphs shows the correct variation of R with T in these fields? Electrical resistance of certain materials, known as superconductors, changes abruptly from a nonzero value to zero as their temperature is lowered below a critical temperature (0). An interesting property of superconductors is that their critical temperature becomes smaller than (0) if they are placed in a magnetic field, i.e., the critical temperature (B) is a function of the magnetic field strength B. The dependence of (B) on B is shown in the figure.
In the graphs below, the resistance R of a superconductor is shown as a function of its temperature T for two different magnetic fields (sold line) and (dashed line). If is larger than , which of the following graphs shows the correct variation of R with T in these fields?
In the graphs below, the resistance R of a superconductor is shown as a function of its temperature T for two different magnetic fields (sold line) and (dashed line). If is larger than , which of the following graphs shows the correct variation of R with T in these fields? Electrical resistance of certain materials, known as superconductors, changes abruptly from a nonzero value to zero as their temperature is lowered below a critical temperature (0). An interesting property of superconductors is that their critical temperature becomes smaller than (0) if they are placed in a magnetic field, i.e., the critical temperature (B) is a function of the magnetic field strength B. The dependence of (B) on B is shown in the figure.
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A conductor lies along the z-axis at 
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