physics

Question 1

require the presence of a medium

Answer 1

em waves

Question 2

Can propagate through empty space

Answer 2

electromagnetic waves

Question 3

are generated by oscillating electric charges

Answer 3

electromagnetic waves

Question 4

carry energy and momentum

Answer 4

electromagnetic waves

Question 5

Cover many frequencies

Answer 5

electromagnetic wave

Question 6

Developed the electromagnetic theory of light

Answer 6

james clerk maxwell

Question 7

his successful interpretation of the electromagnetic field resulted in the field equations that bear his name

Answer 7

james clerkmaxell

Question 8

Developed and explained
Kinetic theory of gases
nature of saturn’s ring
color vission

Answer 8

James clerk maxwell

Question 9

First to generate and detect electromagnetic waves in laboratory settings

Answer 9

heinrich rudolf hertz

Question 10

the most important discoveries were in 1887

Answer 10

heinrich rudolf hertz

Question 11

We will assume that the vectors for the electric and magnetic fields in an electromagnetic wave have a specific space time behaviour that is consistent with maxwell’s equations.

Answer 11

Plane electromagnetic waves

Question 12

assume an electromagnetic wave that travels in the x direction with as shown. the x direction is the direction of the propagation.

Answer 12

plane electro magnetic waves

Question 13

the electric field is assumed to be in the y direction and the magnetic field in the z direction

Answer 13

plane electromagnetic waves

Question 14

waves in which the electric and magnetic fields are restricted to being parallel to pair of perpendicular axes are said to be linearly polarized waves

Answer 14

Plane electromagnetic waves

Question 15

We also assume that at any point in space, The magnitude E and B of the fields depend upon x and t only

Answer 15

plane electromagnetic waves

Question 16

The collection of waves is called a plane wave.

Answer 16

rays

Question 17

is a line along which the wave travels

Answer 17

rays

Question 18

A surface connecting points of equal phase on all waves, called the wave front, is a geometric plane.

Answer 18

Rays

Question 19

surface connecting points of radiation sends waves out radially in all directions.

Answer 19

Rays

Question 20

A surface connecting points of equal phase for this situation is a sphere.

Answer 20

rays

Question 21

Electromagnetic waves transport momentum as well as energy

Answer 21

Momentum

Question 22

As this momentum is absorbed by some surface, pressure is exerted on the surface

Answer 22

Momentum

Question 23

Assuming the wave transports a total energy TER to the surface in a time interval Δt, the total momentum is p = TER / c for complete absorption.

Answer 23

Momentum

Question 24

Various types of electromagnetic waves make up the em spectrum. There is no sharp division between one kind of em wave and the next. All forms of the various types of radiation are produced by the same phenomenon – accelerating charges.

Answer 24

spectrum of em waves

Question 25

Radio Waves? its length and uses

Answer 25

Wavelengths of more than 104 m to about 0.1 m
Used in radio and television communication system

Question 26

Microwaves? wavelengths and its uses?

Answer 26

Wavelengths from about 0.3m to m
well suited for radar systems
Microwave ovens are an application

Question 27

Infared waves? wavelengths and its uses

Answer 27

Wavelengths of about 10-3 m to 7x10- 7 m
Incorrectly called heat waves
produced by hot objects and molecules
readily absorbed by most materials

Question 28

vissible light?

Answer 28

part of the spectrum detected by human eye
Most sensitive at about 5.5 x 10 -7 m

Question 29

More about vissible light?

Answer 29

Different wavelengths correspond to different colors
The range is from red ( V ~ 7x 10-7 m ) to violet ( V~ 4x 10-7 m)

Question 30

Ultraviolet light?

Answer 30

covers about 4x 10-7 m to 6 x m
sun is an important source of uv light
most uv light from the sun is absorbed in the stratosphere by ozone

Question 31

Xrays?

Answer 31

wavelengeths of about 10-8 m to m
Most common source is the acceleration of high energy electrons striking a metal targe used as a diagnostic tool in medicine.

Question 32

Gammarays?

Answer 32

Wavelengths of about m to m
emitted by radioactive nuclei
highly penetrating and cause serious damage when absorbed by living tissue

Question 33

Crab nebula

Answer 33

xray radio waves vissible light infared

Question 34

production of em waves by an antena

Answer 34

EITHER STATIONARY CHARGES OR STEADY CURRENTS can produce electromagnetic waves
The fundamental mechanism responsible for this radiation is the acceleration of a charged particles

Question 35

Hertz experiments

Answer 35

An induction coil is connected to a transmitter
the transmitter consist of two spherical electrodes seperated by a narrow gap
the coil provides a short voltage surgens to the electronics
as the air in the gap is ionized its becomes a better conductor
sparks are include to across the gap of the reseing electrodes where the frequency of the receiver was adjusted to match of the transmitter
in a series of other experiments hertz also showed that the radiation generated by this equipment exhibited were properties
interference, diffraction reflection refraction and polarization
he also measured the speed of the radiation
it was close the know value of the speed of the light