Which of the following describes an electric insulator?
O A. A material that has a low resistance and prevents charges from
moving freely
B. A material that has a low resistance and allows charges to move
freely
C. A material that has a high resistance and prevents charges from
moving freely
D. A material that has a high resistance and allows charges to move
freely

Answer:

Melanin is a protective pigment in skin, blocking UV radiation from damaging DNA and potentially causing skin cancer. Melanin does protect us, but this research shows it can also do us harm.

Definition:

UVA radiation causes lesions or DNA damage to melanocytes, which are the skin cells that produce the skin pigment known as melanin.

Explanation:

Melanin is a pigment that is produced by cells known as melanocytes in the skin of most animals, including humans. This pigment comes in different shades, depending on the genetic makeup of the individual. Melanin comes in two basic forms and can range from yellowish-red to dark brown. Eumelanin is the most common form of melanin and is brownish in color. The other basic form is called pheomelanin, which produces reddish-brown color that is often associated with freckles and red hair. The production of melanin in the individual is determined by several factors.

Genetically speaking, every individual on Earth has approximately the same number of melanocytes. The difference, then, in the production of melanin is affected by:

Exposure to UV radiation: Melanin is produced as a response to UV radiation in order to prevent damage to the DNA in the integument. Individuals, who are exposed to UV light, such as the sun, will produce more melanin for protection.

Genetic makeup: Different ethnicities and cultures are genetically pre-disposed to producing particular shades and amounts of melanin due to inheritance. This is, essentially, one of the primary indicators used in determining race in the human population. It is important to note that this is, and has historically been, a controversial form of human identification.

Size of melanocytes: Melanocyte size varies in different individuals and may lead to a difference in the amount of melanin produced per cell.

Disease conditions: Several diseases may affect melanin production, including albinism, a genetic inability to produce melanin, and vitiligo, a progressive loss of melanocytes.

Answer:

Holes are formed when electrons in atoms move out of the valence band (the outermost shell of the atom that is completely filled with electrons) into the conduction band. (the area in an atom where electrons can escape easily) which happens everywhere in a semiconductor. When an electron and a hole interact and recombine the energy is not transferred into heat energy or thermal vibrations. instead the energy is transferred into an electron within the conduction band which is then promoted to an energy higher in condition band.

Explanation:

So considering that information, electrons and holes make a semiconductor when moving.

platinum is used because it is more stable, provides accurate results and has a broad temperature range.

Answer:

Momentum is a measure of inertia in motion. Momentum is equal to mass multiplied by velocity. A 2250 kg pickup has a velocity of 25 m/s east.

Explanation:

Brainliest please?

Answer:

1,4,3and 2 would happen hope this helps

Answer:

D:because magmetic force are like factor but the angles of MAGNETIC and FACTORS are same as well!!it soposed to be like force and 1 by 1 to be divided and multiply thus...the DECIMAL have nothing to involved!!

Explanation:

HOPE IT HELPS!!

Complete Question

A 10 kg medicine ball is thrown at a velocity of 15 km/hr ( m/s) to a 50 kg skater who is at rest on the ice. The skater catches the ball and subsequently slides with the ball across the  ice.

Calculate the kinetic energy after collision(in joules).

Answer:

 [tex]K.E=70.23J[/tex]

Explanation:

From the question we are told that:

Mass of ball [tex]m_b=10kg[/tex]

Speed [tex]V_{b1}=15 km/hr ( m/s)[/tex]

            [tex]V_{b1} = 4.1667 m/s[/tex]

            [tex]V_{b1} = 4.1667 m/s[/tex]

Mass of Skater [tex]m_s=50kg[/tex]

Generally the equation for conservation of momentum is mathematically given by

  [tex]m_sV_{s1}+m_bV_{b1}=(m_s+m_b)V[/tex]

  [tex]V=\frac{m_sV_{s1}+m_bV_{b1}}{(m_s+m_b)}[/tex]

  [tex]V=\frac {50+10*4.1667}{(50+10)}[/tex]

  [tex]V=1.53m/s[/tex]

Generally the equation for  Kinetic energy is mathematically given by

 [tex]K.E=\frac{1}{2}(m_s+m_b)V^2[/tex]

 [tex]K.E=\frac{1}{2}(50+10)(1.53)^2[/tex]

 [tex]K.E=70.23J[/tex]

Therefore kinetic energy K.E after collision is given as

 [tex]K.E=70.23J[/tex]

Answer: 0.185

Explanation:

Trust bro

The correct answer about law of floatation is, “0.185 kg”.

When a body which is floating in a liquid, the amount of weight of liquid that is displaced by the body's submerged portion equals the body's total weight.

Volume of water that the cup has displaced = volume of cup

Volume of water that the cup has displaced = 0.000250 m³

Mass of water the cup has displaced = Density of water × Volume of water that the cup has displaced

Given that 1000 kg/m³ is the water density,

Mass of water the cup has displaced = 1000 X 0.000250 = 0.250 kg

Mass of water the cup has displaced = 0.250 kg

By law of flotation

Mass of water the cup has displaced = Mass of cup + Mass of pennies

0.250 Kg = 0.065 Kg + Mass of pennies in the cup (in Kg)

Mass of pennies in the cup = 0.250 - 0.065

Mass of pennies in the cup = 0.185 kg

Hence the mass of the pennies in cup came out be 0.185 Kg after solving.

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Answer:

1 L = 1000 mL

125 mL = 125/1000 = 0.125 L

Answer:

0.125

Explanation:

divide by 1 000 to convert mL to liters

Answer:

Ellipse

Explanation:

Most comets have an elliptical path of orbit.

Answer: The shape of the orbit for most comets is: ellipse

Answer:

where is the table?????????

The wire has a length of 0.50 m and a diameter of 2.5 mm and has the least resistance, so, option B is correct.

A substance's ability to obstruct the flow of electrical current is referred to as resistance. It is symbolized by the capital letter R. The ohm, frequently written as a word and sometimes represented by the capital Greek letter omega, is the unit of resistance that is typically used.

Given:

The length of the wire A = 0.50 m and the diameter is 1 mm,

The length of the wire B = 0.50 m and the diameter is 2.5 mm,

The length of the wire C = 0.75 m and the diameter is 1 mm,

The length of the wire D = 0.75 m and the diameter is 2.5 mm,

Calculate the L / Area factor of all the wires as shown below,

L / Area factor of A = 0.50 / π × 0.0005²

L / Area factor of A = 636619.8

L / Area factor of B = 0.50 / π × 0.00125²

L / Area factor of B = 101859

L / Area factor of C = 0.75 / π × 0.0005²

L / Area factor of C = 955414

L / Area factor of D = 0.75 / π × 0.00125²

L / Area factor of D = 152866

As we can see, if the L / Area factor of B is less, then its resistance will be the least.

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Answer:

  I₃ /I₀ = 25%

Explanation:

For this exercise let's use Malus's law

         I = I₀ cos² θ

where tea is the angle between the two polarizers.

When the polarized light passes the first polarizer, the intensity is constant if it is in the direction of polarization.

        I₁ = I₀

the light transmitted by the second polarizer is

        I₂ = I₁ cos² θ

        I₂ = I₀ cos² 45

        I₂ = I₀ 0.5

this light is polarized 45º with respect to the first polarizer

Now let's examine the third polarizer, it is indicated that it has an angle of 90º with respect to the first polarizer, the angle with respect to the second polarizer is

        θ = 90 - 45

        θ = 45º

so the polarizer is at an angle of 45º

let's use Maus's law

         I₃ = I₂ cos² 45

         I₃ = I₀ 0.5 cos² 45

         I₃ = I₀ 0.25

the light that passes through the system is

         I₃ /I₀ = 0.25

as a percentage we multiply by 100

         I₃ /I₀ = 25%

Answer:

Weird

Explanation:

Tara kain tayo sardinas lang ulam

Answer:

Circular motion: find period, find radius, find velocity, find centripetal acceleration 27 V= T a =vºlr=rw

Explanation:

Answer:

Mass, m = 4 kg

Explanation:

Given the following data;

Energy = 3.6 * 10^17 Joules

We know that the speed of light is equal to 3 * 10⁸ m/s.

To find the mass of the substance;

The theory of special relativity by Albert Einstein gave birth to one of the most famous equation in science.

The equation illustrates, energy equals mass multiplied by the square of the speed of light.

Mathematically, the theory of special relativity is given by the formula;

[tex] E = mc^{2} [/tex]

Where;

Substituting into the formula, we have;

[tex] 3.6 * 10^{17} = m * 300000000^{2} [/tex]

[tex] 3.6 * 10^{17} = m * 9*10^{16} [/tex]

[tex] m = \frac {3.6 * 10^{17}}{9*10^{16}} [/tex]

Mass, m = 4 kg

Answer:

Refraction

The rainbow is created because the index of refraction of water droplets changes as a function of wavelength. So, when the light enters the water droplet different colors will bend at different angles thus producing a dispersive effect known as a rainbow.

Answer:

D: Refraction

Explanation:

Refraction is the spitting of the electromagnetic spectrum, or the disembling of colours. For example, white is a mixture of all the colours.

Limiting factors are resources or other factors in the environment that can lower the population growth rate. Competition for resources like food and space cause the growth rate to stop increasing, so the population levels off. This flat upper line on a growth curve is the carrying capacity.

Answer:

they can eat all of the food and kill off the population

Explanation:

if the competition eats all of the food there's no food for the population and they will die off.

Answer:

42.64

Explanation:

2x=2

7x=5

12x=1.4

17.5x=21.5

Answer:

The electromagnetic spectrum in order of increasing frequency is - radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

The frequency of the gamma rays is >3×10

19

m.

Hence, the gamma rays has the maximum frequency in the electromagnetic spectrum.

Answer:

θ₁ = 0.5 revolution

Explanation:

We will use the conservation of angular momentum as follows:

[tex]L_1=L_2\\I_1\omega_1=I_2\omega_2[/tex]

where,

I₁ = initial moment of inertia = 18 kg.m²

I₂ = Final moment of inertia = 3.6 kg.m²

ω₁ = initial angular velocity = ?

ω₂ = Final Angular velocity = [tex]\frac{\theta_2}{t_2} = \frac{2\ rev}{1.2\ s}[/tex] = 1.67 rev/s

Therefore,

[tex](18\ kg.m^2)\omega_1 = (3.6\ kg.m^2)(1.67\ rev/s)\\\\\omega_1 = \frac{(3.6\ kg.m^2)(1.67\ rev/s)}{(18\ kg.m^2)}\\\\\omega_1 = \frac{\theta_1}{t_1} = 0.333\ rev/s\\\\\theta_1 = (0.333\ rev/s)t_1[/tex]

where,

θ₁ = revolutions if she had not tucked at all = ?

t₁ = time = 1.5 s

Therefore,

[tex]\theta_1 = (0.333\ rev/s)(1.5\ s)\\[/tex]

θ₁ = 0.5 revolution

Answer:

The force of gravity will be "0.11874 N"

Explanation:

The given values are:

Density of planet,

Q = 5000 Kg/m³

Inside radius,

r₀ = 1000 m

Now,

The mass of inside sphere will be:

⇒  [tex]m_p=density\times volume[/tex]

⇒        [tex]=5000\times \frac{4}{3}\pi r^3[/tex]

On putting the values, we get

⇒        [tex]=5000\times \frac{4}{3}\times \pi\times (1000)^3[/tex]

⇒        [tex]=85 \ kg[/tex]

hence,

The force of gravity will be:

=  [tex]\frac{Gm_{planet} m_{person}}{r^2}[/tex]  

=  [tex]\frac{6.67\times 10^{-11}\times 5000\times 4\pi\times 85\times 1000}{3}[/tex]

=  [tex]\frac{6.67\times 10^{-11}\times 4\pi\times 425000000}{3}[/tex]

=  [tex]0.11874 \ N[/tex]

2 bar magnets top to bottom with their long axes vertical, the top one with red S on top and blue N on bottom and the bottom magnet with red S on top and blue N on bottom. this diagram shows magnets that will attract each other. Hence option D is correct.

A permanent magnet is an item constructed of magnetised material that generates its own persistent magnetic field. A refrigerator magnet, for example, is commonly used to hold notes on a refrigerator door. Ferromagnetic (or ferrimagnetic) materials are those that can be magnetised and are strongly attracted to a magnet. These include the elements iron, nickel, and cobalt, as well as their alloys, some rare-earth metal alloys, and naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones that are strongly attracted to a magnet and are widely thought to be magnetic, all other substances respond weakly to a magnetic field via one of many different forms of magnetism.

Hence option D is correct.

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Answer:

Option D

Explanation:

Option (A) is incorrect because transmission of few wavelength will procure visibility of only few colours and not all. Option B is also incorrect as refraction index remains same as it does not changes with the change in angle. Option C is also incorrect because changing orientation of only some of the light with not make any significant difference

Option D is correct because sunlight is a unpolarised light  which can be polarised using reflection. Now when sunlight gets  partially linearly polarized after reflection from the lake, it can be viewed by the observer's eye through the lens.

B is the statements provide is a correct explanation. Rotating the sunglasses changes the index of refraction of the lenses, so more light is retracted away from our eyes at some angles.

The refractive index n is defined as the ratio of the sine of the incidence angle to the sine of the refraction angle, i.e., n = sin I / sin r.

The velocity of light c of a given wavelength in empty space divided by its velocity v in a substance, or n = c/v, is also equal to the refractive index.

Rotating the sunglasses changes the index of refraction of the lenses, so more light is retracted away from our eyes at some angles.

Hence option B is correct.

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Answer:

A major challenge in the drug delivery field is to enhance transport of therapeutics across biological barriers such as the blood brain barrier (BBB), the small intestine, nasal, skin and the mouth mucosa.

Answer:

An aqueous stagnant layer that overlies the apical membrane and the subepithelial blood flow are potential barriers to the absorption of drugs that readily penetrate the absorbing cell of the epithelium. The apical, basal, and basement membranes are potential barriers to the absorption of less permeable drugs

Answer:

Explanation:

A cargo spacecraft was orbiting the earth. It is equipped with rocket and has an initial mass of 30 metric ton. It wants to catch up with the international space station to deliver the cargo. So its rocket engine was fired for 1 minute. The engine ejects mass at a rate of 30 kg/s with an exhaust velocity of 3.1 km/s. The pressure at the nozzle exit is 5 kPa and the diameter of exit area is 94.4 cm. What is the thrust of the eng

102 m

Explanation:

The time 0.6 sec is the time it took for the sound to travel from the bat to the moth and back. So it took 0.3 sec for the sound to reach the moth. From the definition of speed, the distance of the moth d to the bat is given by

v = d/t ---> d = vt = (340 m/s)(0.3 sec) = 102 m

Answer:

T = 0.01 Nm

Explanation:

First, we will calculate the angular acceleration of the disk:

[tex]2\theta\alpha = \omega_f^2-\omega_i^2[/tex]

where,

θ = angular displacement = (6.37 rev)(2π rad/1 rev) = 40.02 rad/s

α = angular acceleration = ?

ωi = initial angular speed = 10 rad/s

ωf = final angular speed = 0 rad/s

Therefore,

[tex](2)(40.02\ rad/s)\alpha = (0\ rad/s)^2-(10\ rad/s)^2[/tex]

α = -1.25 rad/s²

negative sign shows deceleration

α = 1.25 rad/s²

Now, we will calculate the moment of inertia of disk:

[tex]I = \frac{1}{2}mr^2[/tex]

where,

I = Moment of Inertia = ?

m = mass of disk = 1 kg

r = radius of disk = 0.13 m

Therefore,

[tex]I = \frac{1}{2} (1\ kg)(0.13\ m)^2[/tex]

I = 0.00845 kg.m²

Now, the torque can be given as:

T = Iα

T = (0.00845 kg.m²)(1.25 rad/s²)

T = 0.01 Nm