please help !!!!!!!!!!!!!!!!!! give the answer to the question i. which lighthouse will be warmer during the day time and why ? ii. which lighthouse will be warmer during the night time and why ? please help

Answer:

λ = 5.4196 10⁻⁷m,  λ = 541.96 nm    this is green ligh

Explanation:

The photoelectric effect was explained by Eintein assuming that the light was made up of particles called photons and these collided with the electrons taking them out of the material.

                     K = h f -Ф

where K is the kinetic energy of the ejected electrons, hf is the energy of the light quanta and fi is the work function of the material.

The speed of light is related to wavelength and frequency

                   c = λ / f

                  f = c /λ

we substitute

                K = h c / λ - Φ

for the case that they ask us the kinetic energy of the electons is zero (K = 0)

                 h c / λ = Ф

                λ = h c / Ф

we calculate

                 λ = 6.63 10⁻³⁴  3 10⁸ / 3.67 10⁻¹⁸

                 λ = 5.4196 10⁻⁷m

let's take nm

                lam = 541.96 nm

this is green light

Answer:

6.9kgm²

Explanation:

For an axis through the center of the rectangle, I = m[(w²+L²)/12

Using the parallel axis theorem, the added value of I = mR² = m[(w²/4 + L²/4]

Adding the 2 expressions,

I = (m/3)*(w²+L²)

I =6.95 kg∙m²

Answer:

335206922km

Explanation:

Pls see attached file

Answer:

The temperature difference [tex]\Delta T = 258.6 \ ^ o\ C[/tex]

Explanation:

From the question we are told that

   The  thickness is [tex]\Delta x = 0.630 cm = 0.0063 m[/tex]

    The  area is  [tex]A = 1.45 *10^{-2 } \ m^2[/tex]

     The rate is  [tex]P = 500 J/s[/tex]

       The  thermal conductivity is  [tex]\sigma = 0.84J[\cdot s \cdot m \cdot ^oC ][/tex]

Generally the rate heat conduction mathematically represented as

       [tex]P = \sigma * A * \frac{\Delta T}{\Delta x }[/tex]

=>    [tex]\Delta T = \frac{P * \Delta x }{\sigma * A }[/tex]

=>     [tex]\Delta T = \frac{ 500 * 0.00630 }{ 0.84 * 1.45 *10^{-2} }[/tex]

=>    [tex]\Delta T = 258.6 \ ^ o\ C[/tex]

Answer:

I will explain the concept of magnetic field and how it can be calculated.

Explanation:

The formula for magnetic field at the center of a loop is given as

B = μ[tex]_{o}[/tex]I / 2R

where B is the magnetic field

R is the radius of the loop

I is the current

and μ[tex]_{o}[/tex] is the magnetic permeability of free space which is a constant 4π × [tex]10^{-7}[/tex] newtons/ampere²

If the magnetic field at the center of the loop is 0, then μ[tex]_{o}[/tex]I = 0

I = 0 which means there will be no current flow in the loop.

Answer:

The final temperature is 61.65 °C

Explanation:

mass of copper pot [tex]m_{c}[/tex] = 2 kg

temperature of copper pot [tex]T_{c}[/tex] = 20 °C  (the pot will be in thermal equilibrium with the room)

specific heat capacity of copper [tex]C_{c}[/tex]= 385 J/kg-°C

The heat content of the copper pot = [tex]m_{c}[/tex][tex]C_{c}[/tex][tex]T_{c}[/tex] = 2 x 385 x 20 = 15400 J

mass of boiling water [tex]m_{w}[/tex] = 200 g = 0.2 kg

temperature of boiling water [tex]T_{w}[/tex] = 100 °C

specific heat capacity of water [tex]C_{w}[/tex] = 4182 J/kg-°C

The heat content of the water = [tex]m_{w}[/tex][tex]C_{w}[/tex][tex]T_{w}[/tex] = 0.2 x 4182 x 100 = 83640 J

The total heat content of the water and copper mix [tex]H_{T}[/tex] = 15400 + 83640 = 99040 J

This same heat is evenly distributed between the water and copper mass to achieve thermal equilibrium, therefore we use the equation

[tex]H_{T}[/tex] =   [tex]m_{c}[/tex][tex]C_{c}[/tex][tex]T_{f}[/tex] + [tex]m_{w}[/tex][tex]C_{w}[/tex]

where [tex]T_{f}[/tex] is the final temperature of the water and the copper

substituting values, we have

99040 = (2 x 385 x [tex]T_{f}[/tex]) + (0.2 x 4182 x

99040 = 770[tex]T_{f}[/tex] + 836.4

99040 = 1606.4[tex]T_{f}[/tex]

[tex]T_{f}[/tex] = 99040/1606.4 = 61.65 °C

Answer:

λ = 428.6 nm

Explanation:

Hello,

In this case, we must remember that the Young's double slit experiment is described by the expression :

d sin θ = m λ

For constructive interference , and:

d sin θ = (m + ½) λ          

For destructive interference , whereas d accounts for the distance between the slits, λ for the wavelength and m for an integer that describes the order of interference . Thus, for the given angle 30º, the distance between the slits is 3.00 μm or 3.00 10⁻⁶ m and the order of interference is 3; we therefore use the destructive interference equation  to compute the wavelength as shown below:

λ = 3x10⁻⁶ sin (30) / (3 +1/2)

λ = 4.286 10⁻⁷ m

Or in manometers:

λ = 428.6 nm

Best regards.

Answer:

The highest percentage of change corresponds to the thinnest rod, the correct answer is a

Explanation:

For this exercise we are asked to change the length of the bar by the action of a force applied along its length, in this case we focus on the expression of longitudinal elasticity

               F / A = Y ΔL/L

where F / A is the force per unit length, ΔL / L is the fraction of the change in length, and Y is Young's modulus.

In this case the bars are made of the same material by which Young's modulus is the same for all

              ΔL / L = (F / A) / Y

the area of ​​the bar is the area of ​​a circle

               A = π r² = π d² / 4

               A = π / 4 d²

we substitute

              ΔL / L = (F / Y) 4 /πd²

changing length

               ΔL = (F / Y 4 /π) L / d²

The amount between paracentesis are all constant in this exercise, let's look for the longitudinal change

a) values ​​given d and 3L

               ΔL = cte 3L / d²

               ΔL = cte L /d²  3

To find the percentage, we must divide the change in magnitude by its value and multiply by 100.

                ΔL/L % = [(F /Y  4/π 1/d²) 3L ] / 3L 100

                ΔL/L  % = cte 100%

b) 3d and L value, we repeat the same process as in part a

               ΔL = cte L / 9d²

               ΔL = cte L / d² 1/9

               ΔL / L% = cte 100/9

               ΔL / L% = cte 11%

c) 2d and 2L value

               ΔL = (cte L / d ½ )/ 2L

               ΔL/L% = cte 100/4

               ΔL/L% = cte 25%

d) value 4d and L

               ΔL = cte L / d² 1/16

                ΔL/L % = cte 100/16

                ΔL/L % = cte 6.25%

The highest percentage of change corresponds to the thinnest rod, the correct answer is a

Answer:

the magnitude of the electric field is 1.25 N/C

Explanation:

The induced emf in the cube ε = LB.v where B = magnitude of electric field = 5 T , L = length of side of cube = 1 cm = 0.01 m and v = velocity of cube = 1 m/s

ε = LB.v = 0.01 m × 5 T × 1 m/s = 0.05 V

Also, induced emf in the cube ε = ∫E.ds around the loop of the cube where E = electric field in metal cube

ε = ∫E.ds

ε = Eds since E is always parallel to the side of the cube

= E∫ds  ∫ds = 4L since we have 4 sides

= E(4L)

= 4EL

So,4EL = 0.05 V

E = 0.05 V/4L

= 0.05 V/(4 × 0.01 m)

= 0.05 V/0.04 m

= 1.25 V/m

= 1.25 N/C

So, the magnitude of the electric field is 1.25 N/C

The magnitude of the electric field is 1.25 N/C

But before that the following calculations need to be done.

ε = LB.v = 0.01 m × 5 T × 1 m/s

= 0.05 V

Now

ε = ∫E.ds

here ε = Eds because E is always parallel to the side of the cube

So,

= E∫ds  ∫ds

= 4L so we have 4 sides

Now

= E(4L)

= 4EL

So,4EL = 0.05 V

Now

E = 0.05 V/4L

= 0.05 V/(4 × 0.01 m)

= 0.05 V/0.04 m

= 1.25 V/m

= 1.25 N/C

hence, The magnitude of the electric field is 1.25 N/C

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Answer:

if this surface has a higher index than in the medium where the light travels, the reflected wave has a phase change of 180º

Explanation:

When a ray of light falls on a surface if this surface has a higher index than in the medium where the light travels, the reflected wave has a phase change of 180º this can be explained by Newton's third law, the light when arriving pushes the atoms of the medium that is more dense, and these atoms respond with a force of equal magnitude, but in the opposite direction.

When the fractional index is lower than that of the medium where the reflacted beam travels, notice a change in phase.

Also, when light penetrates the medium, it modifies its wavelength

              λ = λ₀ / n

We take these two aspects into account, the condition for contributory interference is

            d sin θ = (m + 1/2) λ

for destructive interference we have

            d sin θ = m λ

in general this phenomenon is observed at 90º

           2 d = (m +1/2) λ° / n

          2nd = (m + ½) λ₀

Answer:

Explanation:

Given data

mass of canister= 3.4 kg

force acting on canister= 3 N

initial velocity u= 2.5 m/s

final velocity v= 4.8 m/s

The work done on the canister is the change in kinetic energy on the canister

change in [tex]KE= Kfinal- Kinitial[/tex]

K.E initial

[tex]Kintial= \frac{1}{2} mv^2\\\\Kintial= \frac{1}{2}*2*2.5^2\\\\KInitial= \frac{1}{2} *2*6.25\\\\Kinitial= 6.25J[/tex]

K.E final

[tex]Kfinal= \frac{1}{2} mv^2\\\\ Kfinal= \frac{1}{2}*2*4.8^2\\\\ Kfinal= \frac{1}{2} *2*23.04\\\\ Kfinal= 23.04J[/tex]

The net work done is [tex]KE= Kfinal- Kinitial[/tex]

[tex]W net= 23.04-6.25= 16.79J[/tex]

Answer:

it is going to D. all of these are resistors

Answer:

8.28 V

Explanation:

Using,

N2/N1 = V2/V1.................. Equation 1

Where N2/N1 = Turn ratio of the transformer, V1 = primary/input voltage, V2 = output/secondary voltage

make V2 the subject of the equation

V2 = (N2/N1)V1............ Equation 2

Given: N2/N1 = 2:29 = 2/29, V1 = 120 V

Substitute these values into equation 2

V2 = (2/29)120

V2 = 8.28 V

Hence the rms output voltage of the transformer = 8.28 V

Answer:

The correct option is  d

Explanation:

From the question we are told that

     The  electric potential is  [tex]V = 3000 \ V[/tex]

      The  power is  [tex]P = 60 \ W[/tex]

      The  charge delivered is  [tex]q = 3nC = 3.0 *10^{-9} \ C[/tex]

Generally the power generated is mathematically represented as

         [tex]P = I V[/tex]

=>      [tex]I = \frac{P}{V }[/tex]

=>       [tex]I = \frac{60 }{3000 }[/tex]

=>     [tex]I = 0.02 \ A[/tex]

This  current flow is mathematically represented as

           [tex]I = \frac{q -q_o}{\Delta t }[/tex]

Where [tex]q_o[/tex] is the charge delivered at t=0 s which is 0s

     So

             [tex]0.02 = \frac{ (3.0 *10^{-9}) -0 }{t - 0 }[/tex]

               [tex]t = 1.50 *10^{-7 } \ s[/tex]

               [tex]t = 150 *10^{-9 } \ s[/tex]

Answer:

Yardangs are formed on vertical strata while zeugen on horizontal strata. ... Yardangs are formed on vertical hard/soft layers of rock, while zeugen (this is its plural form) are formed on horizontal bands of hard/soft rocks giving it a more mushroom-like shape. The Great Sphinx of Giza has been sculpted in a yardang

Answer:

C if it is a negitive ion it has more electrons because protons determine what element it is

Answer:

Qsinθ/4πε₀R²θ

Explanation:

Let us have a small charge element dq which produces an electric field E. There is also a symmetric field at P due to a symmetric charge dq at P. Their vertical electric field components cancel out leaving the horizontal component dE' = dEcosθ = dqcosθ/4πε₀R² where r is the radius of the arc.

Now, let λ be the charge per unit length on the arc. then, the small charge element dq = λds where ds is the small arc length. Also ds = Rθ.

So dq = λRdθ.

Substituting dq into dE', we have

dE' = dqcosθ/4πε₀R²

= λRdθcosθ/4πε₀R²

= λdθcosθ/4πε₀R

E' = ∫dE' = ∫λRdθcosθ/4πε₀R² = (λ/4πε₀R)∫cosθdθ from -θ to θ

E' = (λ/4πε₀R)[sinθ] from -θ to θ

E' = (λ/4πε₀R)[sinθ]

= (λ/4πε₀R)[sinθ - sin(-θ)]

= (λ/4πε₀R)[sinθ + sinθ]

= 2(λ/4πε₀R)sinθ

= (λ/2πε₀R)sinθ

Now, the total charge Q = ∫dq = ∫λRdθ from -θ to +θ

Q = λR∫dθ = λR[θ - (-θ)] = λR[θ + θ] = 2λRθ

Q = 2λRθ

λ = Q/2Rθ

Substituting λ into E', we have

E' = (Q/2Rθ/2πε₀R)sinθ

E' = (Q/θ4πε₀R²)sinθ

E' = Qsinθ/4πε₀R²θ where θ is in radians

Answer:

the atom had a dense, positively charged nucleus.​

Explanation:

Ernest Rutherford, based on the experiment carried out by two of his graduate students, established the authenticity of the nuclear model of the atom.

According to the nuclear model, an atom is made up of a dense positive core called the nucleus. Electrons are found to move round this nucleus in orbits. This is akin to the movement of the planets round the sun in the solar system.

Answer:

Current, I = 1.23 A

Explanation:

Given that,

Inductance, L = 35 mH

Resistance, R = 12 ohms

Potential difference, V = 18 V

We need to find current 5 ms after the switch is closed. Current in LR circuit is given by :

[tex]I=I_o(1-e^{-t/\tau })[/tex] ....(1)

Here,

[tex]I_o[/tex] is final current

[tex]I_o=\dfrac{V}{R}\\\\I_o=\dfrac{18}{12}=1.5\ A[/tex]

[tex]\tau[/tex] is time constant

[tex]\tau=\dfrac{L}{R}\\\\\tau=\dfrac{35\times 10^{-3}}{12}\\\\\tau=0.00291\ s[/tex]

So, equation (1) becomes :

[tex]I=1.5\times (1-e^{-5\times 10^{-3}/0.00291})\\\\I=1.23\ A[/tex]

So, after 5 ms the current in the circuit is 1.23 A.

Answer:

The critical angle phenomenon.

Explanation:

Critical angle in optics is the smallest angle of incidence of a wave, that will give total reflection of the wave. This phenomenon occurs at the boundary of two medium, where light will normally move from one medium to another.

To prevent light from entering the water, the angle of incidence of the light incident on the water must exceed the critical angle.

Answer:

Option B: T ≈ 0.16 μs

Explanation:

We are given;

Mass; m = 6.68 × 10^(-27) kg

Magnetic field;B = 0.80 T

Charge;q = 2e

Now, e is the charge on an electron and it has a value of 1.6 × 10^(-19) C

So, q = 2 × 1.6 × 10^(-19)

q = 3.2 × 10^(-19) C

The period of the circular motion of the alpha particles moving along a in the presence of the magnetic field is given by;

T = 2πm/qB

Where ;

m, q and B are as stated earlier.

Plugging in the relevant values, we have;

T = (2π × 6.68 × 10^(-27))/(3.2 × 10^(-19) × 0.8)

T = 0.16395 × 10^(-6) s

This can also be written as;

T ≈ 0.16 μs

Answer:

n= speed of light in vacuum/ speed of light in the other medium.

Explanation:

If light is moving from medium 1 into medium 2 where medium 1 is vacuum (approximated to mean air) and we are required to find the velocity of light; then we can confidently write;

n= speed of light in vacuum/ speed of light in the other medium.

Hence;

n= c/v

Where;

n= refractive index of the material

c= speed of light in vacuum

v = speed of light in another medium.

Note that the refractive index is the amount by which a transparent medium decreases the speed of light.

Answer:

Explanation:

Relation between flux and inductance is as follows

φ = Li

where φ is flux associated with induction of inductance L when a current i flows through it

putting the values

3.25 x 10⁻³ x 800 = L x 2.9

L = .9 H

for induced emf in an induction , the relation is

emf induced = L di / dt

Putting the values

7.5 x 10⁻³ = .9 x di / dt

di / dt = 8.33 x 10⁻³ A / s

(a) The self inductance of the solenoid is 0.897 H.

(b) The magnitude of the rate of change of the current is 0.00836 A/s.

The given parameters;

The self inductance of the solenoid is calculated as follows;

[tex]emf = \frac{d\phi}{dt}\\\\emf = \frac{Ldi}{dt} \\\\d\phi = Ldi\\\\\phi = BA\\\\NBA = LI\\\\L = \frac{NBA}{I} \\\\L = \frac{N\phi}{I} \\\\L = \frac{800 \times 3.25\times 10^{-3}}{2.9} \\\\L = 0.897 \ H\\\\[/tex]

The magnitude of the rate of change of the current is calculated as follows;

[tex]emf = L \frac{di}{dt} \\\\\frac{di}{dt} \ = \frac{emf}{L} \\\\\frac{di}{dt} = \frac{7.5 \times 10^{-3}}{0.897} \\\\\frac{di}{dt} = 0.00836 \ A/s[/tex]

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Answer:

Explanation:

The general decay equation is given as [tex]N = N_0e^{-\lambda t} \\\\[/tex], then;

[tex]\dfrac{N}{N_0} = e^{-\lambda t} \\[/tex] where;

[tex]N/N_0[/tex] is the fraction of the radioactive substance present = 1/16

[tex]\lambda[/tex] is the decay constant

t is the time taken for decay to occur = 8,450s

Before we can find the half life of the material, we need to get the decay constant first.

Substituting the given values into the formula above, we will have;

[tex]\frac{1}{16} = e^{-\lambda(8450)} \\\\Taking\ ln\ of \both \ sides\\\\ln(\frac{1}{16} ) = ln(e^{-\lambda(8450)}) \\\\\\ln (\frac{1}{16} ) = -8450 \lambda\\\\\lambda = \frac{-2.7726}{-8450}\\ \\\lambda = 0.000328[/tex]

Half life f the material is expressed as [tex]t_{1/2} = \frac{0.693}{\lambda}[/tex]

[tex]t_{1/2} = \frac{0.693}{0.000328}[/tex]

[tex]t_{1/2} = 2,112.8 secs[/tex]

Hence, the half life of the material is approximately 2113 seconds

Answer:

Increase in frequency of the laser

Explanation:

Because An increase in frequency will result in more lines per centimeter and a smaller distance between each consecutive line. And a decrease in distance between each gratin

Answer:

toaster- 15.1A

electric frying pan- 11.8 A

lamp- 0.5 A

b) The combination will blow the fuse.

Explanation:

When devices are connected in parallel, the potential difference across each of the devices is the same but the current through each is different. Hence;

V= 120 V

Power= IV

For the toaster;

I= 1820/120 = 15.1 A

For the electric frying pan;

I= 1420/120 = 11.8 A

For the lamp;

55/120 = 0.5 A

Total current = 15.1 +11.8 + 0.5 = 27.4 A

The combination will blow the fuse.

Explanation:    

step one:

Given data

power of toaster= 1,820 W  

power of electric frying pan= 1,420 W  

power of lamp= 55 W  

current of the outlet= 15 A

voltage of outlet = 120 V

step two

since all  three appliances are connected in parallel to the socket outlet, they will use the same voltage of 120 V and the currents will be different across each appliance,

Hence the current across the Toaster will be I₁

using P=I₁V we have

I₁= P/V

I₁= 1820/120 =  15.16 A

A. The current drawn by each device

the current across the  electric frying pan will be I₂

using P=I₂V we have

I₂= P/V

I₂= 1420/120 =  11.83 A

the current across the   lamp will be I₃

using P=I₃V we have

I₃= P/V

I₃= 55/120 =  0.45 A

therefore the total current drawn by all appliances will be

Total current = I₁+I₂+I₃= 15.16 +11.83+ 0.45= 27.44

B.  Will this combination blow the 15-A fuse?

27.44 A > 15 A by 45% ...and this will make fuse to blow

Answer:

The intensity is  [tex]I_1 = 263.35 \ W/m^2[/tex]

Explanation:

From the question we are told that

    The intensity of the beam is  [tex]I = 285\ W/m^2[/tex]

    The  angle is [tex]\theta = 16^o[/tex]

The  intensity of the light that emerges from the polarizer is mathematically represented by Malus' law as

        [tex]I_1 = I * cos^2 (\theta )[/tex]

substituting values

        [tex]I_1 = 285 * [cos(16)]^2[/tex]

substituting  values

        [tex]I_1 = 285 * [cos(16)]^2[/tex]

        [tex]I_1 = 263.35 \ W/m^2[/tex]

The question is not complete so i have attached it.

Answer:

The light source is 2 cm from the bottom of the lamp

Explanation:

From the attached image, we can see that the parabola opens up with its vertex at the origin.

Now, the standard form of equation for a parabola is:

x² = 4ay

Looking at the parabola in the attachment, the top right edge of the lamp has a coordinate of (12,18)

Thus, we have;

12² = 4a(18)

144 = 72a

a = 144/72

a = 2

Looking at the parabola again, the line of symmetry is at x = 0

Thus, axis of symmetry is at x = 0.

Thus, focus is at (0, 2)

So, if the light source is placed at the focus, the distance of the light source from the bottom of the lamp is 2 cm

The distance of the light source from the bottom of the lamp is 2 cm.

The given parameters;

Apply standard parabola equation to determine the distance of the light source from the bottom of the lamp;

[tex]x^2 = 4ay\\\\12^2 = 4a(18)\\\\144 = 72 a\\\\a = \frac{144}{72} \\\\a = 2 \ cm[/tex]

Thus, the distance of the light source from the bottom of the lamp is 2 cm.

"Your question is not complete, it seems to be missing the following information";

the top right edge of the lamp has a coordinate of (12,18)

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Answer:

The box will cover a distance of 0.9199m before coming to rest

Explanation:

We are given;

Angle of tilt; θ = 12°

Speed of sliding down; u = 1.5 m/s

Coefficient of kinetic friction; μ = 0.34

We are told that the box is sliding down an incline tilted at a 12° angle above horizontal.

Thus,

The components of the weight of the block would be;

Fx = mg sinθ = mg sin 12

Fy = mg cosθ = mg cos 12

For, the normal force on the block, it will be counter balanced by the Y component of weight of block and so we have;

Normal force; Fn = mg cos 12

Now formula for the frictional force would be given by;

Ff = μmg cos 12

So, Ff = 0.34mg cos 12

So, the net force along the inclined plane is;

Fnet = Fx - Ff

Fnet = mg sin 12 - 0.34mg cos 12

Where Fnet = mass x acceleration.

Thus;

ma = mg sin 12 - 0.34mg cos 12

m will cancel out to give;

a = g sin 12 - 0.34g cos 12

a = 9.81(0.2079) - 0.34(9.81 × 0.9781)

a = -1.223 m/s²

According to Newton's equation of motion, we have;

(v² - u²) = 2as

s = (v² - u²)/2a

Final velocity is zero. Thus;

s = (0² - 1.5²)/(2 × -1.223)

s = -2.25/-2.446

s = 0.9199 m

Thus, the box will cover 0.9199m before coming to rest

Answer:

0.273m/s

Explanation:

first find out the meaning of 0.90×10−4m3/s

literally, that is 0.9x6 = 5.4m3/s = 3•5.4m/s or 16.2 m/s

1.5 gal/min = 0.00009464 m³/s, perhaps that is what you mean?

cross-sectional area of pipe is πr² = 0.0105²π = 0.0003464 m²

so you have a a flow of 0.00009464 m³/s flowing through an area of 0.0003464 m²

they divide to 0.00009464 m³/s / 0.0003464 m² = 0.273 m/s