<span>A flashlight is an electric-powered light source; the light source is a light bulb or an LED. The electrical energy is converted into visible light. Flashlights can be hand-held or mounted to a platform. Light from a lighting, on the other hand, is formed by exciting electrons to a higher state. </span>
The frequency : a) 7.5 x 10¹⁴ /s
<h3>Further explanation</h3>
Radiation energy is absorbed by photons
The energy in one photon can be formulated as

Where
h = Planck's constant (6,626.10⁻³⁴ Js)
f = Frequency of electromagnetic waves (/s or Hz)
f = c / λ
c = speed of light
= 3.10⁸ m/s
λ = wavelength
The wavelength(λ) of purple light is 400 x 10⁻⁹ m, so the frequency :

Answer:
I'm assuming it would be B, since it makes sense. If not, I'm really sorry.
Explanation:
Answer: 90.04°C
Explanation: <u>Calorimeter</u> is a device measures the amount of heat of a chemical or physical process. An ideal calorimeter is one that is well-insulated, i.e., prevent the transfer of heat between the calorimeter and its surroundings. So, the net heat change inside the calorimeter is zero:

Rearraging, it can be written as

showing that the heat gained by Substance 1 is equal to the energy lost by Substance 2.
In our case, water is gaining heat, because its temperature has risen and so, brass is losing energy:

Calculating:
![m_{w}.c_{w}.\Delta T=-[m_{b}.c_{b}.\Delta T]](https://tex.z-dn.net/?f=m_%7Bw%7D.c_%7Bw%7D.%5CDelta%20T%3D-%5Bm_%7Bb%7D.c_%7Bb%7D.%5CDelta%20T%5D)
![100.4.18.(18.4-15)=-[52.9.0.375.(18.4-T)]](https://tex.z-dn.net/?f=100.4.18.%2818.4-15%29%3D-%5B52.9.0.375.%2818.4-T%29%5D)
Note: final temperature is the same as the substances are in thermal equilibrium.
Solving:
418(3.4)= - 365.01 + 19.8375T
19.8375T = 1786.21
T = 90.04
The initial temperature for the sample of brass was 90.04°.