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ryzh [129]
3 years ago
13

How to revise for science

Physics
1 answer:
Scilla [17]3 years ago
7 0
What is your question exactly? im confused
You might be interested in
What current flows through a 2.60-cm-diameter rod of pure silicon that is 20.5 cm long, when 1.00 ✕ 103 V is applied to it? (Suc
Virty [35]

Answer:

1.13 mA

Explanation:

Length of wire L = 20.5 cm = 0.205m

Radius of wire r = 2.60/2 = 1.3cm = 0.0130m

Voltage V = 1 × 10³ V

Resistivity of pure silicon p = 2300 Ohms • m

Cross sectional area of the wire

A = pi × r² = pi × (0.013)² = 5.307 × 10 ^-4 m²

Resistance of the material

R = p• L/A

= 2300 • 0.205/5.307 × 10^-4 = 0.888 × 10⁶ Ohms

Using Ohms Law

R = V/ I

I = V/R

I = 10³/0.888 × 10⁶

= 0.001126 A

= 1.13 mA

5 0
4 years ago
The Hi line of the Balmer series is emitted in the transition from n = 3 to n = 2. Compute the wavelength of this line for l H a
irina1246 [14]

Answer:

\lambda=550\ nm

Explanation:

The Hi line of the Balmer series is emitted in the transition from n = 3 to n = 2 i.e. n_i=3 and n_f=2

The wavelength of Hi line of the Balmer series is given by :

\dfrac{1}{\lambda}=R(\dfrac{1}{n_f}-\dfrac{1}{n_i})

\dfrac{1}{\lambda}=1.09\times 10^7\times (\dfrac{1}{2}-\dfrac{1}{3})

\lambda=5.50\times 10^{-7}\ m

\lambda=550\ nm

So, the wavelength for this line is 550 nm. Hence, this is the required solution.

6 0
3 years ago
The molecule that traps the sun's energy is ?.
kakasveta [241]
The molecule that trap's the sun's energy is chlorophyll.
7 0
3 years ago
A stereo speaker is placed between two observers who are 35 m apart, along the line connecting them. If one observer records an
kompoz [17]

Answer:

   x = 2,864 m ,       Ra = 32.1 m                       

Explanation:

Let's solve this problem in parts, let's start by finding the intensity of the sound in each observer

observer A β = 64 db

             β = 10 log Iₐ / I₀

where I₀ = 1 10⁻¹² W / m²

              Iₐ = I₀ 10 (β/ 10)

let's calculate

              Iₐ = 1 10⁻¹² (64/10)

              Iₐ = 2.51 10⁻⁶ W / m²

Observer B β = 85 db

             I_b = 1 10-12 10 (85/10)

             I_b = 3.16 10⁻⁴ W / m²

now we use that the emitted power that is constant is the intensity over the area of ​​the sphere where the sound is distributed

              P = I A

therefore for the two observers

              P = Ia Aa = Ib Ab

the area of ​​a sphere is

               A = 4π R²

we substitute

               Ia 4pi Ra2 = Ib 4pi Rb2

               Ia Ra2 = Ib Rb2

Let us call the distance from the observer be to the haughty R = ax, so the distance from the observer A to the haughty is R = 35 ax; we substitute

             Ia (35 -x) 2 = Ib x2

we develop and solve

           35-x = Ra (Ib / Ia) x

           35 = [Ra (Ib / Ia) +1] x

           x (11.22 +1) = 35

           x = 35 / 12.22

            x = 2,864 m

This is the distance of observer B

The distance from observer A

            Ra = 35 - x

            Ra = 35 - 2,864

            Ra = 32.1 m

8 0
3 years ago
A man is pulling on his dog with a force of 34.7 N directed at an angle of 24.4° to the horizontal. Find the x component of this
stepladder [879]

Answer:

31.7\:\mathrm{N}

Explanation:

We can use basic trig in a right triangle to solve this problem. Let the x component of the force be x. We have the following equation:

\cos 24^{\circ}=\frac{x}{34.7},\\x=34.7\cos 24^{\circ}\approx \boxed{31.7}

7 0
3 years ago
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