1
JEE Main 2014 (Offline)
+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 2013 (Offline)
+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 component 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
$$5.80 \times 10.4\,Wb/{m^2}$$
3
AIEEE 2008
+4
-1
Relative permittivity and permeability of a material $${\varepsilon _r}$$ and $${\mu _r},$$ respectively. Which of the following values of these quantities are allowed for a diamagnetic material?
A
$${\varepsilon _r} = 0.5,\,\,{\mu _r} = 1.5$$
B
$${\varepsilon _r} = 1.5,\,\,{\mu _r} = 0.5$$
C
$${\varepsilon _r} = 0.5,\,\,{\mu _r} = 0.5$$
D
$${\varepsilon _r} = 1.5,\,\,{\mu _r} = 1.5$$
4
AIEEE 2006
+4
-1
Needles $${N_1}$$, $${N_2}$$ and $${N_3}$$ are made of ferromagnetic, a paramagnetic and a diamagnetic substance respectively. A magnet when brought close to them will
A
attract $${N_1}$$ and $${N_2}$$ strongly but repel $${N_3}$$
B
attract $${N_1}$$ strongly, $${N_2}$$ weakly and repel $${N_3}$$ weakly
C
attract $${N_1}$$ strongly, but repel $${N_2}$$ and $${N_3}$$ weakly
D
attract all three of them
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