1
JEE Main 2019 (Online) 8th April Morning Slot
+4
-1
A circular coil having N turns and radius r carries a current I. It is held in the XZ plane in a magnetic field B$${\mathop i\limits^ \wedge }$$ . The torque on the coil due to the magnetic field is :
A
$${{B{r^2}I} \over {\pi N}}$$
B
B$$\pi$$r2IN
C
Zero
D
$${{B\pi{r^2}I} \over { N}}$$
2
JEE Main 2019 (Online) 8th April Morning Slot
+4
-1
A thin strip 10 cm long is on a U shaped wire of negligible resistance and it is connected to a spring of spring constant 0.5 Nm–1 (see figure). The assembly is kept in a uniform magnetic field of 0.1 T. If the strip is pulled from its equilibrium position and released, the number of oscillation it performs before its amplitude decreases by a factor of e is N. If the mass of the strip is 50 grams, its resistance 10W and air drag negligible, N will be close to :
A
50000
B
1000
C
5000
D
10000
3
JEE Main 2019 (Online) 8th April Morning Slot
+4
-1
A plane electromagnetic wave travels in free space along the x-direction. The electric field component of the wave at a particular point of space and time is E = 6 V m–1 along y-direction. Its corresponding magnetic field component, B would be :
A
2 × 10–8 T along y-direction
B
6 × 10–8 T along z-direction
C
2 × 10–8 T along z-direction
D
6 × 10–8 T along x-direction
4
JEE Main 2019 (Online) 12th January Evening Slot
+4
-1
The mean intensity of radiation on the surface of the Sun is about 108 W/m2 . The rms value of the corresponding magnetic field is closet to :
A
102 T
B
10$$-$$2 T
C
10$$-$$4 T
D
1 T
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