1
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
The coercivity of a small magnet where the ferromagnet gets demagnetized is $$3 \times {10^3}\,A{m^{ - 1}}.$$ The current required to be passed in a solenoid of length $$10$$ $$cm$$ and number of turns $$100,$$ so that the magnet gets demagnetized when inside the solenoid, is :
A
$$30$$ $$mA$$
B
$$60$$ $$mA$$
C
$$3$$ $$A$$
D
$$6A$$
2
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
A conductor lies along the $$z$$-axis at $$- 1.5 \le z < 1.5\,m$$ and carries a fixed current of $$10.0$$ $$A$$ in $$- {\widehat a_z}$$ direction (see figure). For a field $$\overrightarrow B = 3.0 \times {10^{ - 4}}\,{e^{ - 0.2x}}\,\,{\widehat a_y}\,\,T,$$ find the power required to move the conductor at constant speed to $$x=2.0$$ $$m$$, $$y=0$$ $$m$$ in $$5 \times {10^{ - 3}}s.$$ Assume parallel motion along the $$x$$-axis.
A
$$1.57W$$
B
$$2.97W$$
C
$$14.85$$ $$W$$
D
$$29.7W$$
3
JEE Main 2013 (Offline)
MCQ (Single Correct Answer)
+4
-1
Two short bar magnets of length $$1$$ $$cm$$ each have magnetic moments $$1.20$$ $$A{m^2}$$ and $$1.00$$ $$A{m^2}$$ respectively. They are placed on a horizontal table parallel to each other with their $$N$$ poles pointing towards the South. They have a common magnetic equator and are separated by a distance of $$20.0$$ $$cm.$$ The value of the resultant horizontal magnetic induction at the mid-point $$O$$ of the line joining their centres is close to $$\left( \, \right.$$ Horizontal com-ponent of earth. $$s$$ magnetic induction is $$3.6 \times 10.5Wb/{m^2})$$
A
$$3.6 \times 10.5\,\,Wb/{m^2}$$
B
$$2.56 \times 10.4\,\,Wb/{m^2}$$
C
$$3.50 \times 10.4\,\,Wb/{m^2}$$
D
$$5.80 \times 10.4\,Wb/{m^2}$$
4
AIEEE 2012
MCQ (Single Correct Answer)
+4
-1
Proton, deuteron and alpha particle of same kinetic energy are moving in circular trajectories in a constant magnetic field. The radii of proton, denuteron and alpha particle are respectively $${r_p},{r_d}$$ and $${r_\alpha }$$. Which one of the following relation is correct?
A
$${r_\alpha } = {r_p} = {r_d}$$
B
$${r_\alpha } = {r_p} < {r_d}$$
C
$${r_\alpha } > {r_d} > {r_p}$$
D
$${r_\alpha } = {r_d} > {r_p}$$
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