11- A certain star is 15.7 million light-years from Earth. The intensity of the light that reaches Earth from the star is 2.10 10²¹ W/m². At what rate does the star radiate EM energy?

? 10²⁶W

14-Unpolarized light is incident on a system of three ideal polarizers. The second polarizer is oriented at an angle of 30.0 with respect to the first, and the third is oriented at an angle of 45.0 with respect to the first. If the light that emerges from the system has an intensity of 30.6 W/m², what is the intensity of the incident light?

find the W/m²

15-Two sheets of ideal polarizing material are placed with their transmission axes at 65.0to each other. A third polarizing sheet is placed between them with its transmission axis at 32.5 to the axes of the other two.

If unpolarized light of intensity I₀ is incident on the system, what is the intensity of the transmitted light?

find the I_0.

16- Two sheets of ideal polarizing material are placed with their transmission axes at 65.0to each other. A third polarizing sheet is placed between them with its transmission axis at 32.5 to the axes of the other two.

What is the fraction of the incident light intensity that is transmitted, when the middle sheet is removed?

find the I_0.

18- A police car's radar gun emits microwaves with a frequency of f₁ = 9.40 GHz. The beam reflects from a speeding car, which is moving toward the police car at 36.3 m/s with respect to the police car. The speeder's radar detector detects the microwave at a frequency f₂.

Find the frequency difference f₂ f₁.

find the kHz.

19- How fast would you have to drive in order to see a red light as green? Take = 682 nm for red and = 530 nm for green.

find the m/s.