1
IIT-JEE 2010 Paper 1 Offline
+3
-1

Electrical resistance of certain materials, known as superconductors, changes abruptly from a non-zero value to zero as their temperature is lowered below a critical temperature Tc(0). An interesting property of superconductors is that their critical temperature becomes smaller than Tc(0), if they are placed in a magnetic field, that is, the critical temperature Tc(B) is a function of the magnetic field strength B. The dependence of Tc(B) on B is shown in the figure.

In the graph below, the resistance R of a superconductor is shown as a friction of its temperature T for two different magnetic fields B1 (solid line) and B2 (dashed line). If B2 is larger than B1 which of the following graphs shows the correct variation of R with T in these fields?

A
B
C
D
2
IIT-JEE 2010 Paper 1 Offline
+3
-1

Electrical resistance of certain materials, known as superconductors, changes abruptly from a non-zero value to zero as their temperature is lowered below a critical temperature Tc(0). An interesting property of superconductors is that their critical temperature becomes smaller than Tc(0), if they are placed in a magnetic field, that is, the critical temperature Tc(B) is a function of the magnetic field strength B. The dependence of Tc(B) on B is shown in the figure.

A superconductor has Tc(0) = 100 K. When a magnetic field of 7.5 T is applied, its Tc decreases to 75 K. For this material, one can definitely say that when

A
B = 5 T, Tc(B) = 80 K
B
B = 5 T, 75 K < Tc (B) < 100 K
C
B = 10 T, 75 K < Tc < 100 K
D
B = 10, Tc = 70 K
3
IIT-JEE 2008 Paper 2 Offline
+3
-1

STATEMENT 1 : The sensitivity of a moving coil galvanometer is increased by placing a suitable magnetic material as a core inside the coil.

and

STATEMENT 2 : Soft iron has a high magnetic permeability and cannot be easily magnetized or demagnetized.

A
Statement 1 is True, Statement 2 is True; Statement 2 is a CORRECT explanation for Statement 1
B
Statement 1 is True, Statement 2 is True; Statement 2 is a NOT CORRECT explanation for Statement 1
C
Statement 1 is True, Statement 2 is False
D
Statement 1 is False, Statement 2 is True
4
IIT-JEE 2007 Paper 2 Offline
+3
-1

A magnetic field $$\overrightarrow{\mathrm{B}}=\mathrm{B}_{0} \hat{j}$$ exists in the region $$a < x < 2 a$$ and $$\overrightarrow{\mathrm{B}}=-\mathrm{B}_{0} \hat{j}$$, in the region $$2 a < x < 3 a$$, where $$\mathrm{B}_{0}$$ is a positive constant. A positive point charge moving with a velocity $$\vec{v}=v_{0} \hat{i}$$, where $$v_{0}$$ is a positive constant, enters the magnetic field at $$x=a$$. The trajectory of the charge in this region can be like,

A
B
C
D
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