For an electromagnetic wave the direction of the A) the direction of the electri

Question

For an electromagnetic wave the direction of the A) the direction of the electric field B) the direction of the magnetic field C) the direction of wave propagation D) the direction of the electromagnetic force on a E) the direction of the emf induced by the wave The electric field in unpolarized light: A) has no direction at any time B) rotates rapidly C) is always parallel so the direction of propagation D) can be in any direction perpendicular to the direction of propagation E) remains along the same line but reverses direction randomly and A clear sheet of polarizing material is placed on top of a axes make an angle of 30 degree which each other. The ration of the intensity of light to incident unpolarized light is: A) 1: 4 B) 1: 3 C) 1: 2 D) 3: 4 E) 3: 8 Three polarizing sheets are plated in a stack with the polarizing directions of the first perpendicular to each other. What angle should the polarizing direction of the middle sheet make polarizing di

Explanation / Answer

28. The correct option is C) the direction of wave propagation.

In electromagnetism, the Poynting vector S = c E x B, where c is a constant. The direction of E x B is same as that of the Poynting vector and the Poynting vector represents the directional energy flux or the direction of wave propagation.

29. The correct option is D) can be in any direction perpendicular to the direction of propagation.

For unpolarized light, the direction of electric field is any direction, however always perpendicular to the direction of propagation.

30. The correct option is E) 3/8

The unpolarized light passing through the first polarizing sheet is half of the incident unpolarized light. Through second polarizer, it follows Malus's law. The final transmittance intensity will be 1:0.5*cos2(30o) = 0.375 = 3/8.

31. The correct option is C) 45o

We can eliminate A) and E) because NO light would get through in those cases. Then the amount of light is given by cos2(1)×cos2(2). For B) and D) the angles 1=30o and 2=60o (or vice verse for D)). Then the intensity through sheets 2 and 3 will give 0.1875 of whatever gets through sheet 1. For C) 45o however I get 0.25 of whatever gets through sheet 1. Therefore, the correct answer is C.

32. The correct option is D) the speed of light in vacuum divided by the speed of light in the substance

The refractive index is defined as c/v, where c is the speed of light in vacuum and v is the speed of light in the material. This quantity is always greater than 1.

Related Questions

Navigate

• Browse (All)
• Browse F
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.