Class 12th

Class 12th Physics Electromagnetic Waves

Two infinite planes each with uniform surface charge density +σ are kept in such a way that the angle between them is 30°. The electric field in the region shown between them is given by:

(A)
(B)
(C)
(D)

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Vishal Baghel

Contributor-Level 10

$\frac {I_0} {10} = I_0 \cos^2 \theta$ $\cos \theta = \frac {1} {\sqrt {10} = 0.31 < \frac {1} {\sqrt {2} \quad \text {which is 0.707}$

So,

$\theta > 45^\circ \quad \text {and} \quad 90^\circ - \theta < 45^\circ$

so only one option is correct i.e. 18.4°

Angle rotated should be

$= 90^\circ - 71.6^\circ = 18.4^\circ$

Answer: (A) 18.4°

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10 months ago

For an electromagnetic wave traveling in free space, the relation between average energy densities due to electric (Ue) and magnetic (Um) fields is :

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Class 12th Physics Ray Optics and Optical Instruments

Contributor-Level 9

Kindly consider the following Image

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10 months ago

The angle of deviation through a prism is minimum when

(A) Incident ray and emergent ray are symmetric to the prism

(B) The refracted ray inside the prism becomes parallel to its base

(C) Angle if incidence is equal to that of the angle of emergence

(D) When angle of emergence is double the angle of incidence

Choose the correct answer from the options given below :

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Contributor-Level 9

Kindly consider the following Image

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10 months ago

In a parallel plate capacitor set up, plate area of capacitor is 2 m² and the plates are separated by 1m. If the space between the plates are filled with a dielectric material of thickness 0.5 m and area 2 m² (See fig) the capacitance of the set-up will be ______ ε₀. (Dielectric constant of the material = 3.2) (Round off to the Nearest Integer)

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Class 12th Physics Ncert Solutions Class 12th

Contributor-Level 10

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10 months ago

A 25 m long antenna is mounted on an antenna tower. The height of the antenna tower is 75m. The wavelength (in meter) of the signal transmitted by this antenna would be

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Contributor-Level 9

Kindly consider the following Image

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10 months ago

A resistor develops 500J of thermal energy in 20 s when a current of 1.5A is passed through it. If the current is increased from 1.5 A to 3 A, what will be the energy developed in 20 s.

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Contributor-Level 10

Heat generated in the resistance
H = i²RT
H? = 500 = (1.5)²R (20) ⇒ R = 500/45 = 11.11 Ω
H? = (3)²R (20) = 9 * (500/45) * 20 = 2000 J.

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10 months ago

A conducting bar of length L is free to slide on two parallel conducting rails as shown in the figure. Two resistors R1 and R2 are connected across the ends of the rails. There is a uniform magnetic field pointing into the page. An external agent pulls the bar to the left at a constant speed v.

The correct statement about the directions of induced currents I1 and I2 flowing through R1 and R2 respectively is:

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Contributor-Level 9

Kindly consider the following Image

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10 months ago

For the given circuit, comment on the type of transformer used.

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Contributor-Level 10

Voltage across secondary source
P = V? i? = V? i?
V? = P/i? = 60/0.11 ≈ 545 V
Since voltage across secondary source is more than primary source (220V)
⇒ Step- up transformer.

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10 months ago

Find out the surface charge density at the intersection of point x = 3 m plane and x-axis, in the region of uniform line charge of 8 nC/m lying along the z-axis in free space.

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Contributor-Level 10

According to Question, we can write
E = λ/ (2πε? r) ⇒ σ = ε? E = λ/ (2πr)
⇒ σ = 8*10? / (2*3.14*3) = 0.424 nCm? ²

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10 months ago

A bar magnet of length 14 cm is placed in the magnetic meridian with its north pole pointing towards the geographic north pole. A neutral point is obtained at a distance of 18 cm from the centre of the magnet. If BH = 0.4G, the magnetic moment of the magnet is 1G = 10^-4T

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