The laws of optics also apply to electromagnetic waves invisible to the eye. A satellite TV dish is used to detect radio waves coming from orbiting satellites. Why is a curved reflecting surface (a “dish”) used? The dish is always concave, never convex; why? The actual radio receiver is placed on an arm and suspended in front of the dish. How far in front of the dish should it be placed?

The laws of optics also apply to electromagnetic waves invisible to the eye. A satellite TV dish is used to detect radio waves coming from orbiting satellites. Why is a curved reflecting surface (a “dish”) used? The dish is always concave, never convex; why? The actual radio receiver is placed on an arm and suspended in front of the dish. How far in front of the dish should it be placed?

Similar questions

A light beam reflects off two parallel reflecting surfaces that are = 202 cm long and separated by a distance of s = 65.0 cm. If the beam of light enters this region as shown, with the angle 0 = 25.1°, determine the following. Ꮎ (a) the number of times the light beam reflects off the left surface Have you redrawn the figure with all angles and distances labeled? How is the entrance angle related to the angle of Incidence and the angle of reflection for the mirrors? times (b) the number of times the light beam reflects off the right surface times
The primary mirror of the Hubble space telescope has a radius of 1.2 m, and it has the design shown in this figure (schematically): The secondary mirror at the top has a radius of about 0.15 m. Use the formula for the area of a circle, A= R2 (where R is the radius), to estimate what fraction of the light is blocked by the secondary mirror.
After a long day of driving you take a late-night swim in a motel swimming pool. When you go to your room, you realize that you have lost your room key in the pool. You borrow a powerful flashlight and walk around the pool, shining the light into it. The light shines on the key, which is lying on the bottom of the pool, when the flashlight is held 1.2 m above the water surface and is directed at the surface a horizontal distance of 1.5 m from the edge. If the water here is 4.0 m deep, how far is the key from the edge of the pool? (Given refractive index of water is = 1.33) 1.5 m 1.2 m 4.0 m
Using filters, a physicist has created a beam of light consisting of three wavelengths: 400 nm (violet), 500 nm (green), and 650 nm (red). She aims the beam so that it passes through air and then enters a block of crown glass. The beam enters the glass at an incidence angle of ?1 = 31.5°. The glass block has the following indices of refraction for the respective wavelengths in the light beam. wavelength (nm) 400 500 650 index of refraction n400 nm = 1.53 n500 nm = 1.52 n650 nm = 1.51 (a) Upon entering the glass, are all three wavelengths refracted equally, or is one bent more than the others? (b) What are the respective angles of refraction (in degrees) for the three wavelengths? (Enter each value to at least two decimal places.) (i) ?400 nm (ii) ?500 nm (iii) ?650 nm
When a man stands near the edge of an empty drainage ditch ofdepth 2.80 m, he can barely see the boundary between the oppositewall and bottom of the ditch as in Figure P22.47a. The distancefrom his eyes to the ground is 1.85 m. (a) What is the horizontaldistance d from the man to the edge of the drainage ditch?(b) After the drainage ditch is filled with water as in FigureP22.47b, what is the maximum distance x the man can standfrom the edge and still see the same boundary?
A technician needs to verify that a parabolic mirror intended for use in a telescope has been properly manufactured. The mirror's focal length should be 226 centimeters. How high above the base of the mirror (in cm) should a point on the mirror's surface located 28 cm horizontally from the base be (ie, what should be the value of y at the location x = 28 cm)?
A mirror is rotating, reflecting the incident rays. The angular speed of the reflected ray is wB. VWhat is the angular speed of the rotating mirror, WM? 2WB WB 0.5wB
A laser beam of diameter d₁-1.1 mm is directed along the optical axis of a thin lens of focal length +4.7 cm (see figure below). (a) How far from the lens will the beam be focused? (b) A second positive lens is placed to the right of the first. Light emerges from the second lens in a parallel beam of diameter dy 3.6 mm. Thus the combination of lenses acts as a beam expander. Find the focal length of the second lens. Find the distance between the lenses.
Ray optics is based on the assumption that light travels in a straight line. Diffraction effects (observed when light propagates through small apertures/slits or around small obstacles) disprove this assumption. Yet the ray optics assumption is so commonly used in understanding location and several other properties of images in optical instruments. What is the ustification?
A laser beam of diameter d1 = 1.3 mm is directed along the optical axis of a thin lens of focal length +5.1 cm (see figure below). (a) How far from the lens will the beam be focused?(b) A second positive lens is placed to the right of the first. Light emerges from the second lens in a parallel beam of diameter d2 = 3.9 mm. Thus the combination of lenses acts as a beam expander. Find the focal length of the second lens.Find the distance between the lenses.
Fiber optic cables, such as those used for high-speed communication (Internet & phone services), transmit signals as light pulses through transparent cables. When viewed from one of the ends, you can see these light pulses, but when viewed from the side you can't. Using your knowledge about reflection and refraction, explain how this might work. Is there some physical limitation where this might not work?