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3 years ago

Explain why the intensity of the light in a flashlight beam decreases as the flashlight moves farther away.

Physics

1 answer:

Karolina [17]3 years ago

7 0

Ir=Initial Intensity/Area of spread=Io4πr2
Ir∝1r2

It is seen from this expression that intensity is inversely proportional to the square of the distance. As we move away from the light source the intensity decreases at the rate of square of the distance from the source.

Brightness being the perception of intensity. more the intensity more bright the object is perceived and vice versa.

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A satellite orbits the Earth in an elliptical orbit. At perigee its distance from the center of the Earth is 22500 km and its sp

aleksley [76]

Answer:

$6.09294\times 10^{24}\ kg$

Explanation:

K = Kinetic energy

$v_p$ = Perigee speed = 4280 m/s

$v_a$ = Apogee speed = 3990 m/s

$r_p$ = Perigee Distance = 22500000 m

$r_a$ = Apogee Distance = 24100000 m

G = Gravitational constant = 6.67 × 10⁻¹¹ m³/kgs²

M = Mass of Earth

m = Mass of satellite

In this system the kinetic and potential energies are conserved

$K_p+P_p=K_a+P_a\\\Rightarrow \frac{1}{2}mv_p^2-\frac{GMm}{r_p}=\frac{1}{2}mv_a^2-\frac{GMm}{r_a}\\\Rightarrow \frac{1}{2}m(v_p^2-v_a^2)+GMm\left(\frac{1}{r_a}-\frac{1}{r_p}\right)=0\\\Rightarrow M=\frac{v_a^2-v_p^2}{2G}\times \left(\frac{1}{r_a}-\frac{1}{r_p}\right)^{-1}\\\Rightarrow M=\frac{3990^2-4280^2}{2\times 6.67\times 10^{-11}}\times \left(\frac{1}{24100000}-\frac{1}{22500000}\right)^{-1}\\\Rightarrow M=6.09294\times 10^{24}\ kg$

The mass of the Earth is $6.09294\times 10^{24}\ kg$

3 0

4 years ago

What phenomenon causes the fuzzy image? What kind of lens is used to correct this, and how is it corrected?

Amiraneli [1.4K]

Sample Response: This phenomenon is called chromatic aberration. This happens when light of different wavelengths focuses at different points. A converging lens is used to help light of different wavelengths focuses at a common point.

8 0

3 years ago

Read 2 more answers

Both the electrical force and the gravitational force between two objects share which relationship?

julia-pushkina [17]

Answer:

B. They are inversely proportional to the square of the distance.

Explanation:

The gravitational force between two objects is given by:

$F_G = G \frac{m_1 m_2}{r^2}$

where

G is the gravitational constant

m1, m2 are the masses of the two objects

r is the distance between the two objects

While the electrical force is given by

$F_E = k \frac{q_1 q_2}{r^2}$

where

k is the Coulomb's constant

q1, q2 are the charges of the two objects

r is the distance between the two objects

As we see from the two equations, both forces are inversely proportional to the square of the distance, so the correct option is

B. They are inversely proportional to the square of the distance.

7 0

4 years ago

A wave has a wavelength of 8 mm and a frequency of 14 Hertz what is its speed?

iren [92.7K]

To find the speed you multiply the wavelength and the frequency together.

wavelength = 8mm = $8x10^{-3}$ m = 0.008 m
frequency = 14 Hz

speed = 0.008m * 14 Hz = 0.112 m/s

6 0

4 years ago

Which of the following is an illuminated object?

EastWind [94]

I believe it's b. A flashlight

6 0

4 years ago