# physics

A 75 W light source consumes 75 W of electric power. Typically only about 5% of this energy is emitted as visible light of wavelength 600 nm. (a) Calculate the frequency of the emitted visible light. (b) How many photons per second of visible light does the source emit? (c) Is the frequency of light the same thing as as the number of photons emitted per second?

1. 👍 0
2. 👎 1
3. 👁 1,239
1. (a) frequency = c/(wavelength)
(b) 75 W/(h*f)
where f it the frequency and h is Plank's constant.
(c) certainly not. Frequency does not depend upon brightness. Photons per second does.

1. 👍 1
2. 👎 0
2. By the way, your "posted by" name is an incorrect statement, which disagrees with the facts and the question itself. What is that all about?

1. 👍 0
2. 👎 0

## Similar Questions

1. ### Math

The illumination of an object by a light source is directly proportional to the strength of the source and inversely proportional to the square of the distance from the source. If two light sources, one four times as strong as the

2. ### algebra

The light intensity of a light bulb varies inversely as the square of the distance from the light bulb. The function I(d) = k/d^2 models this situation, where I is the light intensity, d is the distance from a light source, and k

A source emits sound uniformly in all directions. There are no reflections of the sound. At a distance of 12 m from the source, the intensity of the sound is 1.7 × 10-3 W/m2. What is the total sound power P emitted by the source?

4. ### Math

The intensity of Illumination on a surface varies inversely as the square of the distance from the light source. A surface is 12 meters from a light source and has an intensity of 2. How far must the surface be from the light

1. ### physics

An average of 120KW of electric power is sent to a small town from a power plant constant 10km away.the transmission lines have a total resistance of 0.4ohms, calculate the power loss if the is transmitted at 240v.

2. ### physics

A source of sound (1000 Hz) emits uniformly in all directions. An observer 3.19 m from the source measures a sound level of 39.2 dB. Calculate the average power output of the source.

3. ### calculus

The illumination of an object by a light source is directly proportional to the strength of the source and inversely proportional to the square of the distance from the source. If two light sources, one three times as strong as

4. ### Physics

During a brown-out, the electric power company drops the voltage of the power line and the incandescent light bulbs in your house become dimmer. When this happens, the filaments in the bulbs operate at a lower than normal

1. ### physics

Applying Kirchhoff’s Junction Rule, what happens to the power source and current source when the parallel circuit has two branches, each with a resistor, R?

2. ### physics

A small light source located 1 m in front of a 1 m^2 opening illuminates a wall behind. If the wall is 1 m behind the opening (2 m from the light source), the illuminated area covers 4 m^2. How many square meters will be

3. ### science

what happens to the power of an electric circuit if the resistance is decreased?? explain?? i know that as the power increases the resistance decreases why is that?? Power = voltage^2 / resistance. Think again about what you

4. ### Physics question help/ check my answers

The middle two question please check my answers and tell me if I am correct or if there is something I am missing. The first and the last question I need help to understand and complete it. Thank you in advance!!! 1. What is the