Question

PLEASE HELP! TRUE OR FALSE!
The focal point of a concave mirror is a point on the optic axis through which incident rays parallel to the axis will converge.

MULTIPLE CHOICE!
What is the relationship between frequency and degree of refraction?
dispersive media waves of high frequency do not refract at all while waves of low frequency do
dispersive media waves of high frequency refract more than do waves of low frequency
dispersive media waves of low frequency refract more than do waves of high frequency
dispersive media waves of low frequency do not refract at all while waves of high frequency do

MULTIPLE CHOICE!
Why was Roemer's measurement of the speed of light inaccurate?
because man's reaction time was much slower than the speed of light
because the eclipses of Jupiter's were not regular enough
he did not know the accurate diameter of the Earth's orbit

An object is placed 5.00 cm beyond the focal point of a convex lens whose focal length is 10.0 cm. If the object height is 3.0 cm, calculate the image height.

Answer 1

For the first true or false question, it is true.

Answer 2

Answer:

About the firs question.

The first statement is completely true. An image is attached. You can observe than a concave mirror like it's shown, the focal points is on the optic axis, and all rays converge in that point.

About the second question.

A dispersive medium refers to mediums where waves of different frequencies travel at different velocities. In addition, the relation between frequency and degree of refraction of the medium is that waves with lower frequency will bend less when passing through the dispersive medium. For example, if we pass a red light through a medium, and then we pass a violet light, we'll see the difference in the angle of refraction, the violet light will bend more than the red one.

Therefore, the answer to the second question is "dispersive media waves of high frequency refract more than waves of low frequency do".

About the third question.

The reason why Roemer's measurement of the speed of light was inaccurate is: "He did not know the accurate diameter of the Earth's orbit".

At that time, during 1668-1674, the diameter of Earth's orbit wasn't accurate, which added error of delay to his Roemer's measurement. However, he was the first scientist in deduct a finite speed of light, before him, it was known that the speed of light was infinite.

About the fourth question.

For convex lenses we have the relation between distances and highnesses:

$\frac{d_{o} }{d_{i} }=\frac{h_{o}}{h_{i}}$

We have:

$f=10.0 \ cm$

$d=5.0 \ cm$

$h_{o}=3.0 \ cm$

So, we can deduct that the object is $d_{o}=15.0 \ cm$ away from the lens. But, we need to calculate the distance of the image $d_{i}$ with this relation:

$\frac{1}{f}=\frac{1}{d_{o} } +\frac{1}{d_{i} }$

Replacing all values, we have:

$\frac{1}{10}=\frac{1}{15}  +\frac{1}{d_{i}}\\\frac{1}{10}-\frac{1}{15} =\frac{1}{d_{i}}\\\frac{1}{d_{i}}=\frac{15-10}{150}=\frac{5}{150}\\d_{i}=\frac{150}{5}=30$

Now, we can calculate the highness of the image:

$\frac{d_{o} }{d_{i} }=\frac{h_{o}}{h_{i}}\\\frac{15}{30}=\frac{3}{h_{i}}\\h_{i}=\frac{3(30)}{15}=6$

Therefore, the image height is 6 centimetres.