(Solved by Humans)-Module 8 - CH 8 and 9 HW (Homework) Can you please help me with

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?Module 8 - CH 8 and 9 HW (Homework)

Can you please help me with CH 8 & 9 Homework

Module 8 - CH 8 and 9 HW (Homework)
1) The generator at a power plant produces AC at 27,000 V. A transformer
steps this up to 355,000 V for transmission over power lines. If there are
2,050 turns of wire in the input coil of the transformer, how many turns
must there be in the output coil?
_________ turns

2) What is the wavelength of the 62,500-Hz radio wave used by "radiocontrolled" clocks and wristwatches?
_______ m
3) A piece of iron is heated with a torch to a temperature of
743 K. How much more energy does it emit as blackbody
radiation at 743 K than it does at room temperature, 291
K?
E743
E291
__________
4)

What is the wavelength of the peak of the blackbody
radiation curve for the human body(T = 308 K)?
(Enter your answer to at least two decimal places.)
_______?m
What type of EM wave is this?
radio
microwave
infrared
visible light
ultraviolet
x-ray
gamma ray

5) The blackbody radiation emitted from a furnace peaks at a
wavelength of 2.5 10-6 m (0.0000025 m). What is the
temperature inside the furnace?
_______K
6) The wavelength of an electromagnetic wave is measured to
be 160 m.
(a) What is the frequency of the wave?
_______kHz
(b) What type of EM wave is it?
radio

microwave
infrared
visible light
ultraviolet
7) A small object is placed to the left of a convex lens and on its
optical axis. The object is 30 cm from the lens, which has a focal
length of 46 cm.If the object is moved to a position 40 cm
to the left of the lens, what will the image position be? (A positive
value for p, or position, means the image is on the right side of
the lens.)
p =_______ cm
Describe the nature of this new image. (Select all that apply.)
virtual
real
upright
inverted
enlarged
reduced
on the left side of the lens
on the right side of the lens
8) A camera is equipped with a lens with a focal length of 35 cm.
When an object 2.4 m (240 cm) away is being photographed,
what is the magnification?
________
9) List the main types of electromagnetic waves in order of
increasing frequency.
radio waves, microwaves, infrared, ultraviolet light, visible light,
X-rays, gamma rays
radio waves, microwaves, infrared, visible light, ultraviolet light,
gamma rays, X-rays
radio waves, microwaves, infrared, visible light, ultraviolet light,
X-rays, gamma rays
radio waves, microwaves, visible light, infrared, ultraviolet light,
X-rays, gamma rays

microwaves, radio waves, infrared, visible light, ultraviolet light,
X-rays, gamma rays
Give at least one useful application for each type of wave.

10) Aircraft equipped with powerful radar units are forbidden from
turning them on when on the ground near people. Explain why
this is so.
11) Which type of EM wave does your body emit most strongly?
Ultraviolet light.
Visible light.
Microwaves.
Radio waves.
Infrared.
12) Stars emit radiation whose spectrum is very similar to that of
a blackbody. Imagine two stars identical in size, each of which is
at the same distance from us. One of the stars appears reddish in
color, while the other one looks distinctly bluish. Based on this
information, what can you say about the relative temperatures of
the two stars? Which is the hotter?
The relative temperature of a star that is red in color is higher
than that of a star that is blue in color.
The relative temperature of a star that is red in color is lower than
that of a star that is blue in color.
The appearance of a star is independent of its relative
temperature; therefore, more information is needed to compare
the stars.
There is no difference. Both stars are approximately the same
temperature.

How do you know?
The bluish star emits radiation at a higher frequency and,
therefore, a higher energy (temperature).
The reddish star emits radiation at a higher frequency and,
therefore, a higher energy (temperature).
A star's temperature is not uniform due to its internal and surface
temperatures; therefore, knowing only its relative temperature is
insufficient.
A star's temperature is not uniform due to its internal and surface
temperatures; therefore, both stars will have approximately equal
average temperatures.
13) Describe the greenhouse effect that is occurring in the Earth's
atmosphere.
14) How does the ionosphere affect the range of radio
communications?



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