Physics Homework

What color corresponds to the maximum sensitivity of the eye (Fig. 6.2). in bright light? In dim light?

The maximum sensitivity is in the blue-green range which is 507 nm.

What is meant when a medium is described as "dispersive" cite an example of a dispersive medium

When a medium is described as dispersive is when waves are at different frequencies, they travel at different speed. When oil clashes with water is an example of this.

Where must an object be placed with respect to a converging lens to produce an image one focal length from the lens?

When an object lies outside the focal point of a converging lens, the image will be real and inverted

Why wouldn't you want to use a diffuse reflector when shaving or applying makeup?

You wouldn't want to use a diffuse reflector when applying or shaving makeup for reason when light goes on a rough surface light is not reflected in one direction, but instead it reflected in every direction and you are not able to see your own reflection.

Which of the following determines the speed of a wave? (a) wavelength (b) amplitude (c) frequency (d) medium through which it travels

(D) Medium through which it travels

Describe an experiment that demonstrates the particle (photon) nature of light

An experiment that demonstrates this would be photoelectric effect.

Which travels faster in glass: red light or blue light?

Red travels faster in glass, it bends a sharper angle when it enters the glass than blue does.

How could you determine whether a certain green light has a single wavelength or a board distribution of wavelengths.

A certain green light can be determined to only have a single wavelength while a board distribution of wavelength would most likely have more colors than just green in the spectrum

What kind of lens is used to correct for hyperopia (farsightedness)?

A converging lens is used to correct for hyperopia.

What kind of lens is used to correct for myopia (nearsightedness)?

A diverging lens is used to correct myopia.

An incandescent lamp filament having a temperature of 2700 K radiates its maximum spectral power at a power at a wavelength of 1070 nm (compare Fig. 6.1). Is radiation of this wavelength visible to the eye?

A typical human eye will respond to wavelengths from about 390 to 700 nm.[1]

Photographs taken on the moon's surface show colorless sky. Explain why.

Because the moon has no atmosphere.

When you look at most people's eye pupils, they appear black. Use your knowledge of blackbody radiation to suggest an explanation for this phenomenon.

Black body is a material which radiates but absorbs any light falling on it. An ideal absorber and emitter of light. Which this means that people's eye pupils appear black because the eye pupil appears black because it absorbs ay light that falls on the eye pupil.

Why is the sky blue

Blue is the color of the sky is because of the scattering of sunlight by molecules of air. Blue is scatter more and with longer wavelengths, so it appears brighter.

Describe what happens to a two-slit interference pattern as the slits are brought closer together.

D/L = /d. The interference pattern formed by red light is therefore wider than that produced by blue light. As d gets smaller (splits closer together), D get bigger. It is inversely proportional.

What is fluorescence microscopy?

Fluorescence is defined as absorption of light and subsequent reemission at a longer wavelength

What are some difference between laser light and light from a fluorescent lamp?

Fluorescent lamp is white light, white light produced in two steps which include 1. Electrons collide with mercury and UV radiation is emitted 2. UV light interacts with phosphor and visible light is emitted Laser light is single wavelength light and it is monochromatic, coherent and directional.

Why wouldn't you want to use a spectacular reflector as a movie screen.

For a movie using spectacular reflector would not be able work because when some viewers watching the movie screen wouldn't be able to see any light, yet other people watching movie the movie would have too much light that they would be blinded.

What is the difference between interference and diffraction?

Interference is the superposition of two identical waves to create maxima and minima and diffraction is the spreading of waves when they pass through and opening or around a barrier.

State the law of reflection

The angle of incidence equals the angle of reflection.

Describe a two-slit interference pattern made with white light. What color is the central bright fringe? Explain.

The center bright fringe will be white because interference patterns for all component colors have a maximum but the next maximum on each side will be a rainbow of colors with violet having the smallest spacing and red the largest.

Does light travels faster in water or in glass? How do you know this?

Light travels faster in water than it does in glass. I know this because the index of refraction is smaller.

What is the range of the wavelengths in the visible spectrum expressed in nanometers and expressed in meters?

Light visibility ranges from blue light (the shortest in wavelength) to red light (longest in wavelength). The shortest wavelength of visibility is around 400nm which is 4^10'7m and the longest wavelength of visible light is about 700nm which is 7^10'7 m.

Why are different types of color film used for indoor and outdoor photography?

Outdoor film would make daylight and the outdoors look normal, but indoor light bulbs would appear yellow or red in color. Hence two separate films are used in both the cases.

What is phosphorescence?

Phosphorescence is defined as absorption of light and delayed emission at longer wavelength

How do police officers use the Doppler effect to determine the speed of an automobile

Police officers use the radars as a bounce microwave radiation that bounces off vehicles that helps reflect waves; this provides a measure of vehicle speed.

Why is setting sun red?

Red is the color of the sun setting because when the sun is overhead, it appears slightly orange, since some of then light has been removed by scattering. The redness of a sunset can be increased by the addition of small scattering particles to the atmosphere.

Which travels fast in water Red light or Blue light?

Red light travels faster in water because it bends less than blue light does.

Under what conditions would the shadow of a ball on a screen have no umbra?

The condition that the shadow of a ball on a screen that would have no umbra would only be if there was only one light source

Is the critical angle greater at a water-air surface or a glass air surface?

The critical angle is greater at a water-air surface.

Describe what happens to a two-slit interference pattern as the slits are made narrower.

The fringes will be observed, as there will be more room for fringes

Can the image formed by a concave mirror be either larger or smaller than the object? Explain.

The image formed by a concave mirror can either be larger or smaller than the object depends on the light location.

Can the image formed by a convex mirror be either larger or smaller than the object? Explain.

The image formed by a convex mirror must be the same size of the object or smaller. This is because the mirror equation and also the lateral magnification equation.

Why is a telescope of large diameter said to have a greater resolving power?

The resolving power is proportional to the diameter of the telescope. So larger the diameter, the smaller the angle and the better the angular resolution. A telescope with a larger diameter mirror would have better resolving power. Both telescopes have the same diameter primary mirror

Explain why the colors are "reversed in a secondary rainbow.

The secondary rainbow, there is a double the internal reflection and the order of the colors is revered with respect of the primary, so blue is on top and red is on bottom

A spotlight produces a shadow of a ball on a wall. What happens to the size of the umbra as the ball is moved farther away from the light?

The size of umbra would get smaller and smaller the further the ball moves away from light

To magnify print, would you use a convex or a concave or a concave lens?

To magnify print you would use a convex lens.

Why are clouds white on a sunny day?

Water droplets produce a variety of scattered frequencies, the tiniest scatter more blue than other colors, slightly larger droplets scatter slightly more higher wavelengths create green, even larger droplets scatter more red. The overall result is a white cloud, all colors combined make white.

Radio waves and light waves are both electromagnetic. Why do radio and television signals bend around buildings but light does not?

Wavelength of radio waves is much larger than size of both buildings but wavelengths of light is much smaller. So, radio wave refract and light waves do not.

When an object is brought closer to a converging lens, does the image move closer to, or farther from, the lend? Does the image increase or decrease in size?

When the object is brought closer to a converging lens the image moves farther away and increases in size.

Three projectors are adjusted to produce white light on a screen. If you stand in front of the red projector, what color will your shadow be? If you stand in front of the green projector, what color will your shadow be? If you stand in front od the blue projector, what color will your shadow be?

When you block the red light, your shadow would be cyan, because you blocked the red light leaving you with blue and green which makes cyan When you block the green light, your shadow will be magenta, because you blocked the green light leaving you with red and blue which makes magenta When you block the blue light, your shadow will be yellow, because you blocked the green light leaving you with red and green light which makes yellow