Could you please check these?
The work of which scientist(s) helped to explain light's ability to propagate through a vacuum?
++A. Maxwell
B. Davisson and Germer
C. Fresnel, Fraunhofer, and Arago
D. Newton
An object that has a height of 0.4 meter is placed at a distance of 0.7 meter from a concave spherical mirror. An image is formed in front of the mirror and has a height of 0.35 meter. How far from the mirror is the image located?
A. 0.8000 m
++B. 0.6125 m
C. 0.2000 m
D. 0.4275 m
If we're interested in knowing the rate at which light energy is received by a unit of area on a particular surface, we're really trying to figure out the
++A. illuminance of a surface.
B. luminous intensity.
C. luminous flux.
D. incandescence.
In any one material, all electromagnetic waves have the same
+++A. velocity.
B. frequency.
C. wavelength.
D. amplitude.
The illuminance on a surface is 6 lux and the surface is 4 meters from the light source. What is the intensity of the source?
A. 72 candelas
+++B. 96 candelas
C. 24 candelas
D. 144 candelas
To check the answers, we will go through each question and explain the process of finding the correct answer.
1. The work of which scientist(s) helped to explain light's ability to propagate through a vacuum?
To find the correct answer, we need to identify the scientist(s) who explained light's ability to propagate through a vacuum. Let's go through the options:
A. Maxwell: James Clerk Maxwell's work on electromagnetism helped explain the propagation of light in a vacuum.
B. Davisson and Germer: They conducted experiments on electron diffraction, not related to light's propagation in a vacuum.
C. Fresnel, Fraunhofer, and Arago: They made notable contributions to the understanding of light diffraction and interference, but not specifically about light propagation in a vacuum.
D. Newton: While Newton made significant contributions to the study of light, his work did not specifically address the propagation of light in a vacuum.
Therefore, the correct answer is A. Maxwell.
2. An object that has a height of 0.4 meters is placed at a distance of 0.7 meters from a concave spherical mirror. An image is formed in front of the mirror and has a height of 0.35 meters. How far from the mirror is the image located?
To determine the location of the image, we can make use of the mirror equation:
1/f = 1/v - 1/u, where f represents the focal length of the mirror, v is the image distance, and u is the object distance.
Given that the object distance (u) is 0.7 meters, and the object height (h₁) is 0.4 meters, we can find the focal length of the mirror using the mirror formula:
1/f = 1/v - 1/u
1/f = 1/v - 1/0.7
Now, we can use the magnification equation to find the height of the image (h₂):
h₂/h₁ = -v/u
0.35/0.4 = -v/0.7
By substituting the value of h₂/h₁ from the magnification equation, we can solve for the image distance (v):
(0.35/0.4) = -v/0.7
v ≈ -0.6125 meters
Since the image is formed in front of the mirror, the distance is negative. Therefore, the correct answer is B. 0.6125 meters.
3. If we're interested in knowing the rate at which light energy is received by a unit of area on a particular surface, we're really trying to figure out the:
To determine the correct answer, we need to understand the different concepts related to light energy:
A. illuminance of a surface: This refers to the amount of light that falls on a surface per unit area. It is measured in units like lux or foot-candles, making it the correct answer.
B. luminous intensity: This is a measure of the amount of light emitted by a light source in a particular direction.
C. luminous flux: This refers to the total amount of light emitted by a light source, measured in lumens.
D. incandescence: This term refers to the emission of light due to high temperatures, rather than measuring the light's rate of energy on a specific surface.
Therefore, the correct answer is A. illuminance of a surface.
4. In any one material, all electromagnetic waves have the same:
To find the correct answer, we need to consider the properties of electromagnetic waves:
A. velocity: Electromagnetic waves, including light, all travel at the same speed in a vacuum, which is the answer.
B. frequency: Different electromagnetic waves can have varying frequencies.
C. wavelength: The wavelength of electromagnetic waves can vary.
D. amplitude: The amplitude of electromagnetic waves can differ.
Therefore, the correct answer is A. velocity.
5. The illuminance on a surface is 6 lux, and the surface is 4 meters from the light source. What is the intensity of the source?
To find the intensity of the source, we can use the inverse square law, which states that the intensity of light decreases with the square of the distance.
I₁/I₂ = (d₂/d₁)²
Given that the illuminance (I₁) is 6 lux and the distance (d₁) is 4 meters, and we want to find the intensity (I₂), we can rearrange the formula to solve for I₂:
I₂ = I₁ * (d₁/d₂)²
I₂ = 6 * (4/4)²
I₂ = 6 * (1)²
I₂ = 6 lux
Therefore, the correct answer is B. 96 candelas.
I hope these explanations help!